Warehosuse & Office Network

My company has been looking at me for upgrading there network infrastructure but I've never done too much networking. A lot of the networking here has been done by someone who has moved to a different position and they found me to have be as a dedicated to IT. Anything you guys think I should do or recommendations would be awesome, i'm looking to improve my skills and become a better overall sysadmin.

Important Stuff:

• 80,400 sqft Warehouse Building
• 20,000 sqft Office.
• About 10-15 Metal Racks - WiFi will need to be accessible from within racks.
• 3 Zebra TC 1700 - For picking orders.
• 15 Computers in Warehouse - Half of these are wired, half are on wireless.
• 10 Computers in the Office
• 5 Access Points - 1 in Office and 4 in the Warehouse. AC-Lite Access Point
• Patch Panel runs about half of the office.
• 16 Channel 1080 Camera System.

The main issue at the moment is the connectivity to the access points with the Zebra Mobile Scanners. The access points are right were they would be doing anything with network connectivity.

Switching and Routing Equipment:

• Main Switch HP 1920-24G Networking Switch
• Netgear Prosafe 16 Port 10/100 Switch - Server is connected to the main switch so were are already limited right there.
• Netgear Gigabit Switch GS108
• We have two other switches that are 100 that are only connected to a couple of those access points and 5 of the computers.

Heres my issues:

1. The internet coming into the building is coming in with cooper and we have the max twisted pairs coming into the building. We have another building that we are paying over $800/months so that Frontier has a dedicated line going over to the other building. I'm going to be looking at VPN solution for other building to connect to this building. Unless there is something else I can do? Our internet connection is capped out at 20MB with the twisted pairs. I'm currently looking at upgrading or switching to cable please advise on this?
2. I also have an issue with the connectivity to the access points with the Zebra Mobile scanners they get random drops to the access points.

Please advise me on if there are any good upgrades to the system. I have a call with Frontier today about upgrading our internet. We are looking at upgrading switches if there are some good recommendations for 48 Port Switch to replace two in one room.