Help with hacking WordPress 2.5

I am looking to add some custom hacks to my 2.5 blog, so that it suits me better. However, I am having trouble finding the admin files which need editing. I don’t know how you plugin developers do it! There seems to be very little documentation about what does what in the admin files and I have to resort browsing through the code. Unfortunately, my edits never seem to work. Perhaps someone out there could point me in the right direction, either by helping me with the hack, telling me where to find the relevant code or even just pointing me to some detailed documentation. Thanks in advance. The hacks I am attempting are as follows:

1) Hide certain boxes on the Write/Edit page.

My blog is set up so that low privelege users can edit certain posts. I want to hide all the advanced options for them can’t change them. I don’t want to delete these options, just hide them from view. I plan to use a conditional statement so they are only hidden for users of a certain level. Would CSS be the way to go? What would I edit?

2) Hide the Dashboard and other Admin pages.

For similar reasons as above, I want these ‘low-privelege’ users to not have access to some of the Admin pages. I have stripped them of as many capabilities as possible using the ‘Roles and Capabilities’ plugin, but they still have access to some pages I don’t want, namely: Dashboard, Write and Comments. This plugin used to hide the dashboard, however it is now broken. It used “unset($menu[0]);” to do so and I imagine something similar (but slightly different) would do the trick in WordPress 2.5.

I have other things I’d like to do, but these are my main hurdles. Any tips would be GREATLY appreciated.

Cheers