We could be talking about a number of different things here.
Chewing at the feet could be allergy or the hair between the feet may be bothering Maxi. If the hair needs to be trimmed do that, if not I would just watch him. Check with the vet if his feet become inflamed or he chews them to a point that he is injuring himself. Tiki will clean his feet and chew his nails sometimes; it usually means I need to trim his feet and clip his nails
Sneezing is the same; maybe allergy, maybe his nose just itches from something outside. I wouldn't worry about it unless it gets excessive or you see some discharge.
Face rubbing is usually "marking". Either he/she wants your scent on them or their scent on your things. Tiki does this also; I think it is kind of cute
(unless it is in those yucky worms
).
Animals can react as we do to pollens. This may be mild and will go away, but if you see excessive scratching, chewing I would talk to the vet. If it seems like it is bothering him more after he has been outside for a while you could wash his feet and face when you come inside to remove any pollen, mold or dust he picked up from the grass/ground.
I had a boarder collie, years ago, that had very bad allergies. She had to take prednesone (sp?) every spring because she would chew and scratch until she bled; not a pretty site and painful to watch.
Hope this helps.
Judi