Wolfstar covered it really well. You will have a great time if you read up on the campaign rules and make your character according to those rules.
When you look at the Gen Con event catalog, look for adventures that have "A Living Forgotten Realms adv. for levels 1-10." in the description. It can be helpful, though not required, to play them in numerical order. LFR is increasingly bringing in story and the adventures may be more fun in that sequence.
As was said above, yeah, there are a lot of strikers. That said, you should ultimately play what you think will be fun. Come prepared for a team game and join us on the LFR forums to discuss PCs, role-playing, the campaign, etc.
When you are in the RPGA room, look for the free-standing banners that tell you where to find mustering areas. It might says something like "ELTU3-5: Dwarven Cleric" and then you look around the room for the Dwarven cleric. If in doubt, there is an elevated headquarters area where you can ask questions and the people in RPGA red and blue shirts will help. Arriving 15 min before the start of the slot is recommended so you can find a good table with people that have PCs of your same level. You can usually ask around for other relatively new players and find a like-minded group.
Lastly, we are lucky that there are so many RPGA options. The large number of tickets do mean that you can almost always sign up for your other Gen Con needs first and then for the RPGA offerings. I do still recommend trying to sign up this Sunday, but you can focus on non-RPGA first since those can have an extremely short number of tickets.
Welcome to LFR!