Bloodlines on Source

I think it would be rather easy to convert the maps to a newer source engine, but I don't see how the whole tying together of maps, stats, dialogues and Python scripts would work without having the source code.

It would be an enormous amount of work, so much so that I'm certain remaking the game outright would take less time. Bloodlines Resurgence attempted it for a few years before eventually abandoning the project and switching to Unity later.

The problems they ran into

1. The changes Troika made to the engine are still to this day not fully understood. The model and animation format for example have never been fully cracked. Not to mention you'd need to re-rig all the models anyway because VtmB1 used a proprietary implementation for jigglebones because Source didn't support them yet. They did add support for them years later but it would require re-rigging everything that used them.
2. An enormous amount of VtmB1 was done in a hacky way. The developers hardcoded most of the game's logic. In many instances using the Source engine limited the game drastically. A good example is the way the journal works is triggers fire off when you load the level which then populate it. They did it this way due to the game's very short development time and due to struggling with trying to put an RPG onto the Source engine.
3. The amount of developers who are capable of working with the Source engine is extremely small. This was the biggest issue that Bloodlines Resurgence ran into which heavily contributed to them abandoned the engine. It was hard finding out "is xxyy possible" much less finding someone who would actually implement it. 

This is why they ended up switching to Unity as it allowed for recruiting new developers way easier. They could also properly implement a lot of features in the game modularly. They also planned on features like multiplayer with different playable races. And we'd likely be playing it today had CCP not C&D'd it many years ago.
Not easily. It would require a very large amount of reverse engineering. People forget that OpenMW started development in 2008 and still isn't done, they haven't hit 1.0 yet. OpenMW is a massive project that also benefitted from Bethesda's engines being very well understood. Its model format for example was cracked in the early 2000s and there are no shortage of plugins and converter tools for it. 

The only way you could full on create a VtmB1 source port would be to take one of the leaked source engine source codes that exist online, then reverse engineer VtmB1's changes. This would be an enormous amount of work that would be questionably legal, as you'd not just need to worry about Paradox but also Valve.

Some says it does an (uncomparable) great job in handling lip-sincing....

It seems like a lot of work to only get a C&D and that if it was even successfully completed.

Well dang, I guess this was the answer I was looking for. Thank you for being so concise. As for the Source Engine source code, I wonder if what was released for Alien Swarm could be applied.

I wouldn't mind sacrificing one feature in favor of a working engine :/ but that's only my opinion.

Anyway, regarding the proposed expansions I have a few ideas and I hope to put them on action someday....

Any links or such to the proposals Boss?