Why I couldn't connect to my mobile phone about web browser?
For connect to mobile phone you must get a public ip address about GPRS/UMTS from your provider.
Unfortunately some phone carriers forgiven only internal ip addresses (10.x.x.x, 172.x.x.x etc.).
Alternatively , in this case you must use the GPRS/UMTS settings from a other phone carrier but only when data traffic not so expensive there.
More about GPRS/UMTS configuration order by countries you can find under http://www.quickim.com/support/gprs-settings.html
What is the picture resolution by WebCAM function?
The picture resolution should be 640x480 pixel. In some case, depending on mobile phone, the resolution can be 320x200 pixel.
What is the limit for download files from phone?
In current httpd4mobile V1.1 the file size for download from phone is unlimited.
Note: By all previous httpd4mobile versions is the file download limit 256KB.