Let’s try to use logic:
We know that actually Russia is renovating its whole armed forces at a great expense with a quite ambitious program.
Now, in the middle of such an effort they choose to spend money into renovating a plane with structural limits that practically made it useless for the primary role it was designed for, while they have a wide array of more modern planes still in production…
Sound quite absurd to me, also because they have just started a program that would eventually substitute it.

So, IMHO they have decided to renovate just the planes in better conditions and would use the others for spare parts.
It would cost them way less than buying a whole new plane and so fit into the effort made.
It would eventually also include canopies, even if I consider quite incredible that they can have just lost the knowledge to made them.
Maybe they have not the assembly line anymore, but given the numbers involved they can even made them one by one on a bench.

Which shouldn’t be surprising since the MiG-31 carries nearly 3 times the internal fuel of a non CFT F-15.

Hence the absurdity of comparing the two, F-14 and above all F-111 (2,5 M capable)or better what it was initially intended to be, would have been IMHO better choices.

Given that both f-15 and Mig-31 have their main armament carried in semiconformal mode I’ll guess they would have a similar, limited impact on performances, certainly R-33 &R-37 are way larger missiles, but foxhound is a way greater plane also.

What surprises me is the use of up to 3 different combat helicopters (Mi-24/28 and Ka-52). Mi-28N has already been used in combat by Iraq, thus no need to get that badge.

Mi-28n and Ka-52 would operate in tandem with the latter used as a super capable armed scout helo instead of the Iraqi OH-58 and EC 635.
They would preferibly engage mobile units and operate at night, while, as said, Mi-24P would instead support ground troops attacking enemy infantry positions.

P.S.
Q.E.D: Mi-24P pounding Palmyra today.
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RuAf also active in Raqqah province .

https://www.almasdarnews.com/article/russian-air-force-pounds-isis-raqqa/

Ka-52 as well (in the background)

Apparently the Su-24’s, some fighters and helicopters will be staying on

Way too early to say it for certain.
Keeping those is logical
Fencers are the most numerous plane deployed and are still flexible enought to cover different roles so they would keep a line instead of three different ones.
Copters are for CAS and force protection, fighters would control skyes.

Actually it is more a self protection system than a real ECM: it can be useful to avoid being hit by an already launched missile but its effect doesn’t last in time , nor can it cover plane in any head on engagement.
It would be necessary to deploy huge quantities of them in order to cover a sufficient amount of space to allow a strike group to penetrate deeply into enemy lines.

Truce is observed?

It was never a general truce, no rest for Jihadist, like IS, Jabhat al Nusra, Hansar al Sham and so on.

Between the groups that have signed it and loyalist the truce is generally observed, in several villages they have gone some steps further and have given up arms, Russians have set up a coordinement center and have often acted as a(n interested) middleman. Problem is that in many zones pristine rebel are mixed up with Islamist or foreign groups and they face infighting and vengeances.
What seems instead blocked are the Geneva talks, alsobecause situation on field change at such a fast pace thet they are completely out of sync now
.