Small Office / Home Office (SOHO) Network Upgrading

For this week I've been looking at our office network setup and I just want to upgrade it...

Our small office / home office (SOHO) setup:

1. Internet Connection - 1mbps pldt mydsl

2. Router - 150 mbps wifi-a/b/g/n with 1 10/100 wan and 4 10/100 lan ports, single band

3. Setup - All devices are only connected wirelessly. With 1 Lan port extending to my brother's wifi router

4. Connected Devices
>Office: 1PC and a max of 2 laptops
>Brother's router: 1PC and a laptop wirelessly connected
>Others: Probably a total of 4-7 smartphones and a NAS coming this January to serve as Samba, ftp and cloud server.
>Not Connected: CCTV and Smart TV (Ethernet Only / No Wifi)

5. Use - Email, internet browsing, light streaming and social networking. (Upon NAS inclusion, also data-linked records and reports updating and safekeeping)

6. Notables - We use printers. We also have occassional seminars in our place wherein as many as 30+ guests visit us for our company presentation. Some areas of our office not reached by wifi.

Upgrade Solution Plan
>DSL: 3mbps
>Router: 150mbps Wifi-N + Wifi-N Access Point
>Connections: Wired ethernet - Bro's Wifi Router, NAS, CCTV and an additional wifi access point
>Printers: 2 printers are shared to the network through PC USB 2.0. (Printers are shared on the PC)
*The access point will have scheduled usage only and have ethernet connections to the PC and Smart TV.