How can I converse with my Lord for a long time whilst avoiding falling into bid‘ah?

Firstly: 

Du‘aa’ and conversing with one’s Lord is one of the dearest
of actions to Allah, may He be glorified and exalted, because it is one of
the most sincere forms of expressing humility before Allah and because it is
a clear declaration of one’s absolute need for His mercy, and He loves to
see that from His slaves. 

The fear of falling into bid‘ah should not be a cause of
deterring one from doing this righteous deed. The Shaytaan tries to confuse
people with regard to their acts of worship by making them so worried about
showing off or falling into bid‘ah that they give up the act of worship
altogether. The Muslim should beware of that. You have done well to ask
about what is permissible in du‘aa’ and how to go about it. 

Secondly: 

With regard to the Islamic rulings that are mentioned in the
question, we say: 

Making the prostration lengthy when praying qiyaam is Sunnah
and mustahabb, because of the hadeeth of Abu Hurayrah (may Allah be pleased
with him), according to which the Prophet (blessings and peace of Allah be
upon him) said: “The closest that a person is to his Lord is when he is
prostrating, so say a great deal of du’aa’.”

Narrated by Muslim, 482 

Saying a lot of du‘aa’, as enjoined by the Prophet (blessings
and peace of Allah be upon him), is a reason for making the prostration
lengthy. 

Imam an-Nawawi (may Allah have mercy on him) said: 

Standing, bowing (rukoo‘), prostration (sujood) and the
tashahhud are all lengthy pillars or essential parts of the prayer, with no
difference of scholarly opinion, so it does not matter if they are made
lengthy.

End quote from al-Majmoo‘, 4/126 

In the Qur’aan, Allah, may He be glorified and exalted, has
mentioned the lengthy prostration of the righteous when praising and
commending them, as He says (interpretation of the meaning):

“You see them bowing and falling down prostrate (in
prayer), seeking Bounty from Allah and (His) Good Pleasure. The mark of them
(i.e. of their Faith) is on their faces (foreheads) from the traces of
(their) prostration (during prayers)”

[al-Fath 48:29]. 

We have discussed this ruling previously in the answer to
question no. 6834 

With regard to the previous statement on our website that it
is contrary to the Sunnah – and we did not say that it is bid‘ah – see the
answer to questions no. 111889
and 112165. This speaks about
the imam deliberately making the final prostration (sujood) of a
congregational prayer lengthy to alert the people that this is now the final
prostration. This is what is contrary to the Prophet’s Sunnah. As for making
the final prostration lengthy when praying qiyaam al-layl, none of the
scholars said that this is disallowed; rather it is part of the Sunnah. 

Thirdly: 

Something similar may be said about making the sitting for
the tashahhud lengthy. It is narrated in the hadeeth of ‘Abdullah ibn
Mas‘ood (may Allah be pleased with him) that the Prophet (blessings and
peace of Allah be upon him) taught the Sahaabah the tashahhud, then he said
at the end of it: “Then let him choose whatever supplications he wishes.”

Narrated by al-Bukhaari, 5876 and Muslim, 402. 

It says in al-Mudawwanah, 1/192: 

Maalik said: There is no doubt that a man may offer du‘aa’
(supplication) for all his needs, in this world and in the Hereafter, in the
obligatory prayer, when standing, sitting and prostrating. … It was narrated
that ‘Urwah ibn az-Zubayr said: … I call upon Allah for all my needs when
praying, even my need for salt. End quote. 

With regard to offering du‘aa’ whilst praying with the hands
raised, that is only prescribed in the case of Witr at the end of the night
prayers. In other words, when a person has finished his prayers at night
(qiyaam al-layl), he should make his last prayer Witr and after the final
rak‘ah he may raise his hands and offer whatever supplication he wants, as
the people do with the Imam in Taraweeh prayer in Ramadan. 

Fourthly: 

With regard to du‘aa’ after praying Witr before dawn, there
is nothing wrong with that either and it does not come under the heading of
bid‘ah, because offering du‘aa’ during the time before dawn is permissible
according to the texts of the Qur’aan and Sunnah. 

Allah, may He be glorified and exalted, says (interpretation
of the meaning):

“(They are) those who are patient ones, those who are true
(in Faith, words, and deeds), and obedient with sincere devotion in worship
to Allah. Those who spend (give the Zakat and alms in the Way of Allah) and
those who pray and beg Allahs Pardon in the last hours of the night”

[Aal ‘Imraan 3:17]. 

It was narrated from Abu Hurayrah (may Allah be pleased with
him) that the Messenger of Allah (blessings and peace of Allah be upon him)
said: “Our Lord, may He be blessed and exalted, comes down to the lowest
heaven every night when the last third of the night is left, and He says:
‘Who will call upon Me, that I may answer him? Who will ask of Me, that I
may give him? Who will ask Me for forgiveness, that I may forgive him?’”

Narrated by al-Bukhaari, 1094; Muslim, 758 

Fifthly: 

With regard to seeking out the hour when supplications are
answered on Friday in order to offer du‘aa’ at that time, this also comes
under the heading of righteous deeds and it is not bid‘ah at all. But it is
not permissible to connect it to a naafil prayer after ‘Asr, because
offering naafil prayers after ‘Asr is not allowed. Hence it is sufficient
for the one who wants to offer supplication to sit and do so – whether he is
in the mosque or at home – and to ask Allah for all his needs with sincerity
and humility, and he will be answered, by Allah’s leave. We have discussed
this in detail previously in the answer to question no.
112165 

And Allah knows best.