I lived aboard in the Inner Harbor for a while, July 4th it is one huge nonstop party, and if you arrive Saturday you will not find ANY place to tie up or anchor. If you want to tie up, you should call all marinas soon - few places can fit your cat, summer rates are $2+ per foot per night, and EVERY place to tie up WILL be occupied that weekend.
I have not been out on the docks of the Inner Harbor Marina, but have talked to liveaboards there and they like it. Federal Hill might block your view of the fireworks, but I don't know. On holiday weekends I find the Inner Harbor and Fells Point areas too crowded, and there is wa-a-ay too much alcohol consumption
for me to enjoy it.
The same people own Baltimore Marine
Center (BMC), Baltimore Marine Center - Baltimore, MD
which is before the Inner Harbor, is very nice, has a long dock that can easily fit your cat, and an excellent view of the fireworks. There is a West Marine
on the property and grocery store across the street, and it is walking distance to two water taxi docks and Fells Point.
If you want to anchor, very few people anchor in the area between BMC and the First Mariner Bank building, in front of the Korean War Memorial Park, and you should have room to anchor there. Just stay closer to shore or BMC because it is a turning basin for tankers that unload at the tank farm next to the bank building. If you don't want to take your dink to Fells Point or the Inner Harbor, all the shore there is rip rap, but there is a water taxi dock at the park, so depending on how strong you are and big your dink is, you might be able to get it out at the dock and lock it to a tree in the park.
If you do anchor, be prepared for dredging up toxic black goo, diapers, trash bags and such. Hose it off very well before putting your anchor away, and wash your hands! Talking to any divers about the ear, nose and lung infections they get should cure your urge to anchor anywhere near B-more.
Last year the fireworks lasted 18 minutes.