Disclaimer: I am not a home inspector. I am going by the pictures, and things that have happened to me before.
From the photos:
The central air may be not working at all or not working well - you can see the outside unit at the back of the house, but there are window or portable air conditioners in two of the bedrooms and the living room. The home inspector should be able to tell you the age of the central A/C by looking at the serial numbers. If it's original to the house, or 20+ years old, the cheapest thing to do may be to replace at least the outside unit, inside coil, and lines. I would plan on at least a couple of thousand dollars for this.
I can't tell exactly what the siding is. If it's aluminum or vinyl, or even wood, you are in good shape. If it's "fiber cement" siding, it may contain asbestos. I have an idea (which I'm not exactly sure about) that the "shingle" type of siding is more likelyto have it than the "long board" type, but that may not be true. As far as I know, the current thinking is that if it's in good shape, and not shattering or splintering or crumbling anywhere, the best thing to do is leave it alone. You might check to see if the city or county has any requirements about removing it, especially on a rental property.
The "popcorn" in the popcorn ceilings of that era may also contain asbestos. You can scrape off a little of the popcorn and have it tested to find out. I had this in my previous residence, several years ago, and at that time the EPA guidance I found online was that one of the valid ways to deal with it, if it was otherwise in good condition, was to paint over it. Again, check with the city or county for any requirements they have.
A couple of the downstairs bedrooms appear to have egress windows. You might check on the local code requirements to make sure those are legal.
One of the upstairs bedrooms is either missing a chunk of drywall (not hard to fix) or has had its closet walled off, which might make it not-a-bedroom anymore, legally.
In 1970, the house was probably born with grounded outlets everywhere, which is good. It might have some aluminum wiring - the home inspector may or may not be able to confirm this. The way to tell for sure is to take off the receptacle and switch covers, and the breaker box cover (carefully), and look at the wires, but not all home inspectors will do this. If you do have aluminum wiring, think hard about rewiring, at least for the circuits that have it.
There is no visible outlet near the sink in the bathroom - this is required by code. (Or, it might be out of view to the right of the picture.) When the house was built, it may have been in the base of the light fixture over the sink, and then got removed when that newer light fixture and cabinets were installed. Modern code would be for there to be a dedicated 20 amp circuit with a GFCI receptacle. This is usually not too hard to add.
The circuit breaker panel looks like it might be newer than the house - this is usually a good sign. You might cast a more critical eye on the wiring in the basement that was done after the house was finished. Usually, in my experience, the wiring that was done at the same time as the house was done correctly to the then-current code, but wiring added later is of more variable quality.
There's a silly length of flexible pipe instead of a gutter downspout, to the right of the front door. This may simply be the current owner not wanting to buy a downspout because they're selling it, and it's at least an attempt to keep water away from the foundation, but that might also be telling you that water comes in on that corner.
This is tricky to do, but if you can schedule an inspection or visit an open house right after it's rained a lot, you can sometimes see if the basement has a water problem. If it's occupied, also look for dehumidifiers down there. The home inspector will look at the visible parts of the wall inside the basement for cracks and evidence of past leaks.
It looks like it has an attic fan. If it's working, it can save a little money vs. running the A/C for a few weeks in the spring and fall. However, the tenants have to know how to use it - mainly that they should open some windows before switching it on. If they don't, it can sometimes blow out the pilot light on the water heater and furnace (if equipped). If you don't want that, it may be better to remove it, if it's not a requirement in your market.
In general, for a 1970 house:
The drain plumbing might be cast iron. If so, parts of it have probably already been replaced with plastic (it rusts out). You may need to replace more of it - the horizontal runs go bad beforethe vertical runs, in my experience. This is not too hard to DIY, but sometimes you need two people, just because the pipe you're cutting out is heavy.
I hope this helps!
