Hello,
You should consider the Cisco RV325 for the router and a WAP371 for the access point. They both support the Vlan trunking and will give you very good performance.
RV325 datasheet...
Yes, you should consider a Gigabit switch that support multicast traffic (video streaming). The Cisco SG500 series switch would be a very good choice.
SG500 datasheet below...
The wireless signal transmits at a 90 degree angle from the antenna. Thus is straight up, the signal would be transmitted sideways. This is preferred if device is at eye level. If you need the signal to transmit up to a second floor, then lay the antenna down level with the table.
The Cisco Sg300 or the SG500 series switch is a very good choice for a Layer 3 switch. Thus you could eliminate the 2dn router. This will improve performance. The SG500 switch is the recommended solution. The SG500 gives you excellent processing power.
WiFi signal range is determines by your WAP's antenna gain. The higher the gain the better. You should consider a WAP with a gain of 5dBi like the Cisco WAP561.