Smile [Q] Xperia Pro - Rooted - Can I Use The Restricted RAM Space?

Hello,
Yesterday I rooted my Sony Ericsson Xperia Pro MK16i (4.0.4 - 4.1.B.0.587) & Bootloader is unlocked ( I am fine with it ). As per Xperia Pro Specification, it has 512 MB RAM of which 320 MB Accessible. I would like to know that now after rooting the device, can I use/access those restricted RAM out of that 512 MB? What is the technique by which Sony restricted 192 MB RAM?

Furthermore, I installed Titanium Backup, it is showing my System ROM status as 419 MB of which only 111 MB is free. Can I free some space in ROM?

I have one final question. I deleted some of those pre-installed stupid apps using Root Explorer and done the backup using Titanium. Now If I do factory reset, will it restore all those apps along with Gingerbread OS? ( I updated Xperia Pro to ICS using Sony Official Update Service ). If not, than can I set my factory reset point to the current state of my phone?

I know I asked a lot of questions. But I thought it is better to ask all my questions in one thread rather than opening thread for every query. I will be grateful if you kindly answer my questions.