The house had the carpets all ripped out because of the cat piss and poop...and it's still completely all over the place.

Also the flooring call United carpet and ask for Jim Reed let him know I sent you.

Porch, carport, carpet, landscaping..etc would need repair or complete updating. 

Other than the obvious option of having a conversation and trying to get the tenant to either begin paying or ask them to leave, what rights would I have to get them out and if anyone has experience, how messy can this process get if the tenant is uncooperative?

I'm just trying to cover my butt here and not get wrapped up in something that could get messy and/or hurt my reputation by doing something out of ignorance.

Appliances and hot water heater 12 year life span, hvac 20 year life span, floors 10 year life span except for carpet then 5 year life span, bath and kitchen remodel 20 year life span. 

People will take scrap wood, metal, broken appliances, extra tile, carpet, etc.

Supposedly they took it upon themselves to replace the carpet at their own expense a year or two ago.

If this doesn't make sense for your area then a coat of paint and carpet is usually sufficient.Now touching on your second question.

New floors, cabinets, paint, carpet, AC unit.