New switch and router help

[Delnith]

I recently got a TP link 8-port gigabit switch as well as a Cisco Linksys EA3500 router. I have a lot of computers and machines that need ethernet but was also looking to better my wifi signal in my part of the house. Aside from the houses "main" router, runs 1 ethernet cable to my room.

 

Here is where the questions begin:

1) Should I take the ethernet from the main router and first plug it into the switch or the router?

2) How/where can I find the information to make my new router into a switch/wireless access point?

3) If I were to connect an external hard drive via usb to the access point, how would I best secure it so that only I can put files onto it, but may allow others to read files from it?

 

Thank you, I am still looking for guides elsewhere online but wanted your thoughts and help as well!

[Accidentx13]

1. Switch, then you can add as many end devices to that switch
2. EA3500 should have a feature in the wireless tab to turn it into an WAP, almost all wireless devices have this feature
3. You cant to my knowledge, anyone on your network can access it or hacks your wirelss. Best to get a NAS, many security there. FreeNAS is good