I reached level 50 on gen 7 last night, but still have a little bit of work to do on the challenges (though not much). The tougher challenges for me mainly involve using a titan to kill a titan. Not my style, tbh. Play to your strengths - I prefer to use titans to kill pilots and use pilots to kill titans (usually with rodeo).
Requirements to Next Level:
If It Moves... (G2A4) Tiers: 10, 25, 50, 100, 200 - Done
Top Gun (G2A4) Tiers: 5, 15, 30, 50, 75 - Done
If It Moves... (XO-16) Tiers: 10, 25, 50, 100, 200 - Done
Titan Killer (XO-16) Tiers: 10, 20, 30, 40, 50 - Currently approx 45
Titan Killer (Charge Rifle) Tiers: 1, 3, 5, 7, 10 - Done
Fresh Squeezed (Pilot Melee Kills) Tiers: 1, 5, 10, 15, 25 - Currently approx 14
I'm definitely not a fan of the G2A4 (or infact anything that's not fully automatic), but I got the last few kills I needed yesterday, and have now switched to the CAR SMG. I definitely prefer the Carbine, but the SMG will do - and means I'm earning a few amped ones ready for next gen.
My K/D ratio changed yesterday. That's a bit surprising, tbh - when you've played about a hundred hours it's hard to have any real effect on your stats. Went up from 1.0 to 1.1 though.
I expect it'll stay there forever now. I think I probably average around 1.3, but basic maths indicates I'd need to play another 100 hours at 1.3 to make my average k/d move up from 1.1 to 1.2