-I will create my own legion with its colors, but, can I pretend they are issued from Black Legion or another one so I can play Abaddon or other units (downloaded the codex and keywords stuff is misleading me)
It's generally accepted that you can play any faction you want, regardless of the color scheme you choose, except if a tournament rules says otherwise.
To my understanding, only official
GW tournaments are affected by such limitation. In a casual / local setting, especially in France, this will be a non-issue.
-I read that basic Space Marines are not that good in current meta, but it is best to test paint basic troops imo... so should I drop USD60 in those even though I may not field them ?
It's suspected that
GW is phasing the old marine units/models by making the new primaris models more desirable, but
ofc they won't say it not to alienate the countless players who invested alot of money in their old
SM armies. They are gradually expanding the primaris range, and we reached a point where oldmarines are barely needed anymore. I believe the only thing primaris infantry does not have are lascannons.
To answer your question, old marines are generally less interesting to field than primaris and incidentally, primaris models look much cooler).
-I' like to play a melee style focused army with some support but I read that 8th edition is favoring the shooting, any hints yet on how 9th will play ?
8th favors shooting (that's an understatement, shooting is tactically superior to melee all the way
atm). None of 9th rules have been clearly explained, they "say" that some tweaks were made to make melee more viable (ie not die before turn 2 before being able to hit anything), but from the look of it, melee armies won't suddenly overpower shooty armies overnight, they'll just get more of a fighting chance.
-What is command points farming ?
I think the best way to answer your question is that
CP farming will be gone in 9th edition.
