I don't see any reason why a bike like that wouldn't work for your commute. A very common sized 27 inch tire is 1.25 which works out to about a 32 mm. If the gravel is fairly well packed, I'd think a 32 would be OK.

As far fenders go, just buy a set with the understanding that you can return them if they don't fit. I'm guessing they will.

If the rack has a "dog leg" (a third post on each side), it can take just about any pannier. If not, it'll still work but you'll be better off getting panniers with a rigid side so that they don't swing into your spokes.

One problem with the 27 wheel size is that there aren't as many tires to choose from. I don't know what's available in sizes larger than 1.25 inch. It is possible to convert to 700c wheels on a lot of those bikes. The only concern is the brakes. If there's enough adjustment in the pad placement so that they can be slid down 4mm or more, you should be good.