Tape out everything you plan to have out there: table, chairs, walking space. Tape out the porch dimensions. Or use spray paint, whatever works. It’s the best way to decide

It’ll help you visualize whether you would have room for outdoor play space for games like cornhole, putting golf balls, whatever.

Seriously?? A foot? A dining table and chairs is tight on the ten feet. : ) You want no pots or accent planting to delineate the patio? Listen to the arch, it's less to mow .

what does your town home association say- usually there are bylaws - if the patio is impermeable it may also be a zoning consideration

IMO 12’ would be better I find we use our deck a lot more than grass so bigger is always better and honestly 10’ is pushing it for a dining table and chairs .