Ruckus can activate a shield, if you are finding it hard to kill him then purchase "wrecker" from the item shop, getting it to tier 3 shreds through his shield.
Ruckus is a jack of all trades. He can build more towards damage, support, or tankiness. Either way, his miniguns are contenders in the "Top DPS" market, and any Ruck can deal a surprising amount of damage in a short time. If he ults, just run.
Ruckus' average position relies on what legendary card he picks. If he has Recycler, he'll often be to the side of the objective, if he has Flux Generator he'll usually be on the objective. If he has Aerial Assault he may be above your team.