curve 8320 gprs+speed doubt

[win32.tr0jan]

I have a Curve 8320 from Vodafone.I recently unlocked it,and is on AirTel now.
Now I want to access the internet without BB data plan,to get some themes apps and games from somewhere outside the AppWorld.I have seen many good themes and stuff at places like themes4bb.com .I activated GPRS and Opera mini is working fine(Although it shows 'Installing' everytime I open it,where in Java phones,after the first 'Installing',it always comes as 'Loading'...please lemme know why).But when I browse to download the .jad file,opera opens the link in BB default browser which works only with the BB data plan.Is there any way I can disable/delete the default browser so that everything will be done by Opera?I read in Opera.com that opera will open download links in the download manager of the phone.If thats the only solution,which is the best download manager for 8320?

Also give me some tips to make my phone a lil more faster.It takes almost 10sec to open BeeTag whereas E63 gets it in 5sec!!! I have only 2 apps now,just BeeTag and SmartBattery.[Am having a 512MB SDCARD,empty completely]

Will the speed increase if i Wipe the phone and install fresh OS?Or just upgrade to the newer one?

One last thing:
How can I turn off the camera shutter sound?Atleast change it?

Thanks
Loads of questions,I know...I searched a lot to get expert tips...found this place now only.Others were really awful!

[blackberry-unlocking710]

Here is a good way to solve your issues: you can download the files using your computer internet connection. and then transfer it all to your Blackberry device and install it.