Hi & welcome to BBF
1) I charge my Blackberry every day so I am not the one to give your advice on battery life
2) Have a look at this link for bluetoothing files which may help Transfer files / media via Bluetooth - BlackBerryFAQ
3) I do not think there is anything you can do to boost the EDGE signal, my phone contstantly alternates between EDGE and GPRS.
4) I do not think upgrading to OS 4.5 will improve your EDGE reception. Yes, it will void your warranty but only if they know you have another carriers 4.5 OS installed.
5) Is Monilink compatible with Blackberry? I have just googled it and it does not have my bank listed but it looks like a cool application. Are byou trying to run it via BIS? you may need to run it through Orangeworld.
BB weather does not work for me either I use a wap site, The weather channel.co.uk, they have a shortcut icon for the desktop too
There are many free applications, I like Viigo, an rss news reader, there is a BB forums version of it too. What kind of applications would you like to have?
MSN messenger currently works best with Jivetalk but with the 4.5 OS and BIS 2.5 it will work as a stand alone application and will be free. This may be dependant on your carrier, Orange, allowing it.
I hope this answers some of your questions
Ask more if you need to.