Besides that with basically every home built prior to 1980 will have some foundation issues because of the clay soil here in Texas, it's a given to allocate for problems. 

We have cruddy clay soil that moves constantly and causes all sorts of issues with the slab foundations, resulting sheetrock cracks, etc. 

There are quite an amount of adhesive off the floor underneath to get rid off and I was wondering what would be the best way to get rid of all the adhesive on the floor? 

The driveway might have some cracks due to tree roots underneath it.

Kitchen and bath wet areas.Flushing areas.Window and door seals.Around all penetrations (hose, faucets, duct work from vents, fireplace and chimney vents).Vinyl, aluminum or wood siding.Stucco or mortar cracks.Interior settling or shrinkage sheetrock cracks.If you have a basement and it has a sump pump, check to make sure it is operating properly, clean the pump screen and remove any soil buildup from the well.Clean and repair gutters.

I posted an ad, say 80' long 10" deep trench of mostly sandy soil and for them to give a quote by email.  

If you haven't cleaned it yet of course It will smell awful.The carpet underneath is it subfloor or concrete.

Your survey company is supposed to give a topographic survey telling you what the current elevation of the ground is, and then an engineer is to test your soil to tell you what you're building on.

I think as Wayne said you can add a new roommate and amend the existing lease with an addendum.I would also screen the new roommate and make the addition of this roommate contingent upon him passing your screening.Also will have to make it clear to your tenant and new roommate that once he is added he inherits "everything".If your current tenant has damaged a wall or soiled the carpet prior to the roommate's occupancy, this roommate is now liable to these damages.

The exterior is smooth with no tell-tale lines from cinderblock, or whatever that stuff is underneath.