There is Alter road (private) launch, $5 a launch, no perks, just basic access with a pot hole parking lot. than there is St Jeans launch ($10) that is a little better with bathrooms and a paved gated parking lot but steep ramps with short docks. alter road and St Jeans are street names off of Jefferson. exit 222A off I94 is the outer drive exit and if you turn and take it towards the water it turns into alter, St Jeans is the next exit west of Alter/Outer Drive and gotta make a couple turns. I have a small boat and use Alter many times and hardly use St Jeans but with a women joining the trip i would use St Jeans because of the bathrooms and gated lot.
On Jefferson just below Alter, there is a bait shop called Moe's where you can get what you need. If your coming from Gross Point and entering Detroit, it would be on your left couple doors down from the gas station(gas station on corner of Jefferson and Alter).