Please help with a wireless router & wireless printer problem with Macbook pro

Please be kind as this is my first post and really last resort as I've tried EVERYTHING to get this wireless router up and working.. I may not use the right terminology but I'll try and explain as best as I can...here is my issue.

The hardware:

1 x Imac (mid 2008) running OS 10.6.8

1 x Macbook Pro (2013) running 10.8.2.

1 x Telstra 3G Dongal which is modem number MF626 (approx 2 years old)

1 x Samsung SCX-3405FW multifunction laser printer with wireless capabalities.

1 x TP Link TL-MR3220 wireless router

What I am trying to do:

Use my dongal in the router to access the internet on both computers

Use the router with my printer attached to it to create a network so I can print wirelessly from all computers.

What is happening (OR NOT):

The router is being configured and is showing up in my network preferences, however the internet will not work on either computer through this network and I've had to go back to the old method.

I have added the printer following Samsung specifications and it shows up on both computers. It prints perfectly on the router formed network on the imac, however the Mac Book Pro is doing very weird things and is taking at least 5min for the printer dialogue box to show up and has randomly frozen all other programs until it does. It caused my wireless keyboard to turn off and my USB mouse perhaps part of the system freeze. Once the dialogue box finally shows up it is taking up to 5min to recognise any command (pages to print). When it does finally let me hit the "print" button it just says The printer is not connected. I let it sit for 5min and suddenly it prints the page????? what on earth is going on?

I should mention that as soon as I turn airport off the printer dialogue box pops up immediately.

I have been down to the local tech shop and they are at a loss as to why it's doing it and offered my money back on the router. They also advised I need a username and password on the Telstra dongal but there is none provided and it shows up as optional in the router set up. I've updated the firmware for the router and I'm ready to throw the retched thing out the window.. has anyone had anything like this happen before or know what I'm doing wrong.. I tried downloading the .bin file in the router configurations as well and it's not helped.

I have sent requests to technical support at TP-Link and am still waiting to hear back from them but I wonder if anyone can give me some ideas. Am totally out of my depth here but must have done something right to get the Imac to work, but am at a loss as to why the macbook pro is freaking out. I'm sure it's a really simple ticked box or command I haven't done right. Please help before I go insane!!