Erie? Medium. You're reeling in drift socks all day, no way I've be fishing MH out there. I use medium Okuma GLTs for early season board fishing on Lake Ontario. Super cheap and do the job, also double up for Gbay salmon/trout fishing as well.
As for downriggers, Scotty would be my choice. Grab a set of the 1106s or 1116s (Dual rod holders) and you'll be set. Add some 15lb weights and you're golden.
Are you planning on running a mast or inline boards? If inline there are a bunch of choices (Church, Offshore, etc)