Ademco Vista Honeywell Alarm 20p

TRizzi, it really helps me understand a post if it has standard punctuation, so I don't have to go over it several times to separate out the sentences and phrases to see what goes together. Here's how I interpreted your post:

I have 3 FA215 keypads and I would like to upgrade at least one. if not all.

So from the first sentence (if I've separated them correctly), I gather you'd like to upgrade one or more of your FA215 Keypads. Those KPs would have originally been installed with a First Alert control panel, rather then the Honeywell Vista-20P panel you now have, so I'm guessing they're kind of old now. You didn't mention what features you want in your upgrade, but I'd recommend you get at least one Honeywell 6160 Alphanumeric Keypad with its 2-line display, which will give you full capability to program your panel (the Vista-20P). You could replace the other 2 KPs with 6160s, or you could use 6150 KPs, which are "Fixed-English" KPs like your FA215s, that display zone numbers but no Alphanumeric descriptors. You really only need one programming keypad, although the Alpha display (E.g., "FAULT FRONT DOOR") can be nice.
Touchscreen keypads are fashionable and cool, but be aware that they are power hogs and may require an additional power supply at the control panel to incorporate them. "Additional Power Supply" in alarm jargon means (1)an additional 16.5VAC 40VA transformer; (2)the power supply PCB to convert the AC to 12VDC output, typically with at least 500mA capacity (1A or more would be better); and (3) a separate backup SLA (Sealed Lead Acid) backup battery like the one backing up your Vista-20P. You can use a 4AH or 7AH battery, depending on how many and what kind of devices you're backing up.
However, if you decide you want touchscreens, I would still recommend having at least one 6160 Keypad: They're more reliable for panel programming.
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I have a Vista 20P, both hardwired and sensors in the house.

I don't quite understand this 2nd (?) sentence. Did you mean to type that you have both hardwired and wireless sensors in the house?
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I also have a 5882 hooked up to my panel that works but I believe that some RF keypads could eliminate the use of that I could be wrong on that ? But thats the way I understood after doing some research .

You can replace the the 5882 RF Receiver with a 6150RF or 6160RF Keypad, which have built-in transceivers---but why would you? In general, installing a keypad/transceiver combo unit is to hold down the cost and labor of the initial installation. The RF KP costs less than the combined cost of the 5882 and a keypad, but more than either separately; but since you already have a 5882 (either ENL, ENM, or ENH) installed, it would make no sense to spend extra for an RF KP and have to disconnect a (presumably) working 5882. Your Vista-20P can only have one RF Receiver.

Also, an independent RF Receiver is usually located in a more centralized location than keypads, which tend to be located where keypads are convenient, and may or may not be the best Receiver location. If your wireless reception has been working, I don't recommend changing it.