Networking Help

Right now I'm planning on adding access points to our building (20,000 Sq.ft.) with light walls in between (metal studs). Just mainly the offices need the best coverage which is 3/4 building so I plan on placing APs concentrated around them. I'm taking into consideration that we wont really know how many we need since there are a million factors that play into range/speed so this is the starting point after I did a crude survey plan online. I plan on running Cat6A to the AP's since right now all the offices are hard wired with 5E. If everything goes according to plan, it should be about 20 wireless phones/computers would be on the network at a given time and 5-6 hardwired also.

Currently we have Spectrum business class internet, two modems, one dedicated to WiFi and one dedicated to the switch. The switch is a 32p (cheap $30) that runs to the Networking rack (that connects to each office). And the WiFi router is located in the networking room which gives little/no WiFi anywhere in the building. I got the approval to upgrade this place since it's.... bad and have to limit downtime since we deal with medical info. I'm semi-knowledgeable, not an expert like people here so I figured I would get some advise on the best approach to take. This is a Non-profit organization so I could get the Cisco AP's for cheaper to offset the price of a Ubiquiti AP and cloud-key.

Here are the options

1.) 7 x Cisco Aironet 1850 Series a/g/n/ac Access Point with Mobility Express 2.) 5 x Ubiquiti AC PRO (and a Unifi Cloud Key) My questions are:

1.) Does Mobility Express have a fee that you have to pay monthly? I'm pretty sure no.

2.) Does the Cisco AP's need to used with a Cisco Switch? And hopefully no fees for Cisco switch.

3.) Would someone rather choose #1 or #2? I prefer Cisco (if there are no fees) since it's Wave 2.

4.) And can anyone recommend a switch (48p) (preferably between 300-400 range)? Doesn't need to be managed or have POE since the Ubiquiti comes with injectors and I could always get injectors for the Cisco ones.

Thanks for reading and any advise!!