You can usually get away with a small 1 - 2" lift that will allow you to run 31's. Body lifts are cheap, but they can cause other problems, especially with automatics. It's better to raise the suspension versus raising the body off the frame.
Cheapest "suspension" lift you can do to a first gen is usually a spacer underneath the coil and a shackle lift in the rear.
If you have a junkyard near you then you may be able to source some F150 coil spacers (do a search here and you should find plenty of info about them).....but they seem to be getting harder and harder to find. You can buy some spacer lift kits and those will run around $120 or so. Also, you can make your own spacers, which is what I did...but that turned out to be a 3-day process which involved some welding and general tinkering and while it works, if I had to do it again - I would've just bought the kit. Shackle lifts are fairly straight forward.....you replace the stock spring shackle with one that is longer which effectively increases the distance between the spring and frame.....shackles are usually under $50.
If you're wanting to run 33's, you're looking at at least a 4" suspension lift kit but you may encounter some rubbing issues, so a 5.5" would be best - but the price on those runs around $700 for a bargain basement kit and around $1000 for a quality kit.
As to your question about manual hubs and auto hubs......
Manual hubs require you to get out and manually turn the knob on the hub to lock the hub to the prop shaft. Most people who actually wheel prefer manual hubs because they don't fail as easily, they're stronger, and they don't unlock unless you unlock them or they break which means they stay locked no matter what direction the wheel is turning. The biggest con is that if you're stuck axle deep in mud and need to engage the hubs....you're getting dirty.
Auto hubs biggest advantage is convenience....they will engage when you engage the transfer case due to the speed differential between the shaft and the wheel itself so you don't have to get out of the truck to lock the hubs. However, this is also one of the biggest disadvantages....if you change directions then the hub unlocks and then locks again which can induce a failure during rapid forward and reverse motion. They're also weaker than manual hubs due to their design.
If you're not doing anything serious then you should be fine with the auto hubs, but you might want to switch to manual hubs in the future. You can find some Rangers around the early 90's model years than had Warn manual hubs on them which was an option IIRC, which makes it a lot cheaper to convert to manual hubs, otherwise you're looking at around $150+ to do a conversion.
