you can check on the status of your pro challenges by hitting the x button when on the perk you are trying to reach pro level on.
i usually check it after each match to see what progress i am making towards my goal.
i believe the deal with capturing the flag is that you don't actually have to capture the flag, but you need to be in possession of it once during its trip back to being captured
for example: you grab the flag, immediately get killed, but a teammate picks it up before the enemy can "return" the flag, it still counts as a CAP for you towards your goal.
i could be wrong, but i did read this somewhere.
you can also play HC and kill the flag runner and cap it yourself, or play with some teammates who will take one for the team and die so you can take the flag in for the cap, i've helped a few people out along the way. lightweight will enable you to sprint further without having marathon pro, so its a good combo to use both. i think you also need some offensive kills for lightweight pro, so CTF works well for both.
once you obtain marathon pro you will be able to sprint non-stop
you will find it to be very useful and rewarding during game play, especially if you are chasing someone, need to get somewhere fast, or like the run and gun strategy
i have played a little more HC.
not sure if i was playing with shitty people, but i did surprisingly well.
i started with HC CTF, and then played some HC FFA.
i think ghost pro probably helps me not get noticed.
you have to dial back the run and gun a little bit and be more observant and pay attention to traps, hiding spots, and campers