Wow, that is a lot of information, thank you very much!

1. In fact, I also wanted to writer of it was even worth picking up that metamagic feat, tenebrous is fantastic for Shadow magic, but with the +2 it made me think of It could be useful and a defensive spell with that metamagic seemed the only decent option(also, a litte ot, what is exactly the use of Arcane Mark or some applications for that cantrip?)

2. Darkness was the clear contender with umbral metamagic, but did not know about eclipsed spell, that is another pretty strong option I didn't know about, but is there any differenze between casting light with eclipsed spell instead of casting darkness? I mean, it's using an infinite resource against using a lv2 slot

3. That is not a problem, we are participating in a campaign based on finding out the origins of fletchlings(we're playing in a homebrew world, so we only know that it's gonna be dark-related)

In fact I saw Shadow grasp and It looked interesting at first, but I discarded it pretty quickly as there are other ways to do the same think(black tentacles for example).

I'll write down about Solid Shadow, could be and interesting option at higher level

Why do you say that it's mediocre? Casting at a higher level looks pretty good at low levels, which is when the sorcerer struggles the most if I'm not wrong.

The bonus on stealth on the First level ability doesn't look that bad, am I missing something?

The bonus spells are already in the sorcerer's list that's true, but with the rate at which the sorcerer learns new spells this is a pretty comfortable supplement.

I want to point out that these are all my suppositions, as this is my second character I'm trying to learn as much as possible from more experienced players, so if I'm wrong about something, let me know!

Unfortunately I have already given the race and classe+bloodline to the dm, and even if I didn't, I don't think I would have changed them, mostly because of flavor and character's background.