You are correct. A non-resort "Marriott Suites" property is simply a non-resort Marriott property for the purposes the Marriott Bonvoy terms & conditions. It's the same brand.

Guaranteed Lounge Access and the Welcome Gift upon arrival are two separate benefits. As a Titanium Elite member, you get both, as you correctly noted. When there is no lounge, you get breakfast in the restaurant. Although it only needs to be a "continental breakfast," most Marriott properties provide a full breakfast if there is no lounge or the lounge is closed.

If it were a Sheraton Suites property, then daily restaurant breakfast for member + 1 would be a Welcome Gift option.