i got to rank5 yesterday then logged on this morning and my guy was gone so i made a new one. then i couldn't even start the first mission, the race one. so i deleted the 39mb patch in the xmb > system data i think it was, re downloaded and installed, bam fired right up, got to rank8. i hope it stays this time. missions are all launched from your phone or the blue mission markers. you launch then you can invite your crew members. you are very limited at first. you have to do the lamar race, then lamar makes you buy some clothes and you rob a store, then the gerald mission where you jack some drugs, then you have to launch and complete a last team standing mission gerald tells u to do, then a simeon mission where you repo a car. after that more and more types of missions will unlock for you, and you can call gerald for missions and ppl call and text u new missions.
the best missions ive found are survival missions unlocked at rank 15. a rank 15 has to launch it but any1 can join. you survive waves of enemies as long as you can. you keep all the weapons you get for the mission too. i left with an assault rifle, combat mg, smg, and a rocket launcher lol. someone get to rank 15 pls and invite us so we can rank up fast and get the big boy dollars and guns!