Double posting again, sorry. Forgot to offer advice on the whole mech purchase question.
With 23 million you can kit out a pretty good MadCat and begin grinding out mech skills and stuff. This is where choosing cheaper mechs from the IS side might be an advantage though.
To move on to the second tier of the Mech Skill/Pilot Skill tree, you need to hit basic proficiency on three variants of the same chassis. That means if you want to get the mech skills maxed for T-Wolfs, you need to save up the 15+ million credits for another 2 variants as well.
Buying a BL-KNT is cheaper per chassis, leaving more money for weapons and upgrades like DHS, Endo or FerroFib armor, and engines. Then you still have money left to buy an entire other IS mech, or another BL-KNT, or whatever.
Both will serve you well, its more a matter of do you want to be able to try out more mechs besides the one you are grinding and the trial mechs, or is one mech for the moment ok? Oh, that's another thing. Aside from the Origins Clan mechs, Clan Mechs are locked to a single engine and you can't upgrade the speed at all unless you get to Tier 2 Proficiency and unlock Speed Tweak. Take that into consideration too. You're going to be travelling a lot slower in a Clan mech, generally, than IS mechs in your same weight class because they can switch engines at will.