I cannot resist recommending two less-well-known churches very near where you'll be staying.
Closest and most visually impressive is Santa Prassede; street signage spells the church name somewhat differently. It's small (the opposite of Santa Maria Maggiore), so only a minor time commitment. It has stunning 9th-century mosaics. Free entry, but take a couple of 1-euro coins to feed the light boxes for a better view. As of last winter the hours were 10-12 and 2-4.
Just a bit farther away and even older (with a 4th century mosaic) is Santa Pudenziana. Its hours were 9-11:30 AM. You may need light-box coins here, too; I don't remember.
If you get the munchies at an odd time, the Mercato Centrale at Termini Station could be useful. It's far better than the typical US food court, that's for sure. However, it was very crowded at the time of my visit, so you might want to avoid it if you're worried about picking up COVID. I bought something to eat and carried it outside the market area to eat it.
I liked the Gelateria Santa Maria Maggiore, located at the fork in the road where Via S. M. Maggiore/Via Panisperna branches off Via Cavour. This would be quite close to your lodging. They don't have a particularly wide selection of flavors, but Google shows a rating of 4.7, so I'm not the only one who likes it.
Your visit is short enough that you probably won't need to branch out from Italian food, but if you want something different, I can recommend Restobar Saaz, an Indian place on Via Cavour.
Although I didn't take full advantage of the restaurants in the area, Monti has some very nice, gentrified streets with many restaurants to explore. It's the area north of Via Cavour (SW of where you're staying).
I was exceptionally lucky with the weather; I don't think it was ever colder than the monthly averages shown in the temperature charts. However, it was quite chilly on February mornings, not climbing to 40F until close to noon. You'll probably need a warm layer (and maybe rain gear); you might want to have a bag with you for stashing your outer garment if/when it really warms up in the afternoon.