There are several that would work. It partly depends on what frequency you want to amplify. Many/most people will discourage the use of inline amplifiers because they often add more problems than they solve. They often increase noise, overloading, and intermod problems. I would suggest them only if you live in a pretty rural area where there is not a lot of radio noise in the area. A better solution than an amplifier is a better/higher antenna with better/shorter coax. Directional antennas are a good bet in most situations to pull in something weak.
Yes, pre-amps will work; however, you must realize that for the most part, they only have limited appeal. They amplify everything, including noise. So, if you are attempting to hear something that you can't hear already, it isn't going to work. They may help clean up some signals, but as I said they amplify ambient noise also. The Harahan/River Ridge area there is full of electrical noise, not to mention interfering signals, so I think that you probably won't get a lot of use out of it there. I use one here to help out during temp-inversion periods for helping on some of the remote sites on the SD VHF system, but mostly it just sits there.
However, if your coax run from antenna to receiver is a very long one (for whatever reason), then in addition to using the best LMR series coax you can handle, you may also want to put a good amp at the antenna end to overcome the coax losses.
True, however I am not aware of a low gain affordable mast-mounted (weatherproof) amp for 800MHz. They seem to be more common in the HF/Ham world. If you know of one for the hobbly level that has about 3 to 8dB gain that reaches to 800MHz, let me know.
I'm using Stridsberg multicouplers, which work well, but they are at the radio end of the coax.