LinkedIn yes, Indeed no. Almost all recruiters (internal and external) are active on LinkedIn. It definitely doesn't hurt to have a good profile... people will reach out to
you.
Recruiters get a lot of scorn, but I've had good experiences with them as long as you understand their incentives. They usually get some percentage of your starting salary, so let's say they make 15k if your offer is 100k (making up these numbers, but probably in the ballpark. Also, they only get paid if you stick around for at least a few months). If your offer is for 120k, they might make 3k more, so they have some incentive to get you a higher salary, but really, their incentive is to close as many deals as possible. Better to close two deals for 15k each then to drag out one deal for 18k.
As long as you understand that their incentives are somewhat aligned with yours but not completely, you might have a good experience with recruiters. I've found some who are great and many others who suck. But the good ones will get you in the door with the right people and guide you through the interview process.