Congratz! I have two car seats in they E90. One back facing and one front facing. One sunshine and one britax (frontier) for front facing. Got the sunshine initially for its compactness. But the britax is much easier to buckle. Can show u how they look/fit so u can make ur decision. : )
As for protection, I got those lion heart full seat protection. Folks on the forum have also recommended to add a cloth underneath for add protection.
U'll have a blast! My 3 year old was saying "wee!" at age two whenever we go on an on ramp. : )