Portsmouth breweries I can think of:

Cisco (formerly redhook) At Pease (big!)

Downtown:
Portsmouth Brewery (original brewpub, fist in state and one of earliest generally)
Earth Eagle (smaller but has some food. love it.)

Not far from downtown down Islington ST:

(I can't remember which have food options others likely to chime in.)
Liars Bench
Great Rhythm
Loaded Question

I'm sure I am missing some but that is an easy day tour.

If you skip Cisco you can walk em all in an epic trip (2 miles) starting at Loaded Question and heading into downtown. You should have a place to crash downtown cuz gonna get sloppy. I made a map that included a couple of pubs too. Lemme know if interested.

For Italian in Downtown Portsmouth:

Ristorante Massimo - very fancy! you will need reservation well in advance.

Cafe Mediterraneo - Classic nice Italian restaurant - reservation probably good also as weekends are hard in general for walk in for any restaurant downtown.