Your first question is unclear, so I do not fully understand what it is that you are trying to accomplish. It seems that you would like to access the network remotely for administration purposes and/or allow remote access for end users by way of remote desktop connection; however, you are concerned that once you provide a user with the IP address, they then have the ability to use it freely.
Now I am not privy to how the network is setup in its entirety, but it appears that Windows Server 2003 is running in the environment. Is this a workgroup or domain based network? If it is domain based, you should consider setting up the routing and remote access service (RRAS) to allow access to the network remotely in a controlled manner, according to centralized policies. This will allow you to configure who can access the network, when they can access it, what IP address they get assigned and any routes available to them. The simplest way to do so is by establishing a PPTP connection, which packs its own encryption. Alternatively, you can use L2TP but it does not have its own encryption, so IPSec is required.
To answer your second question, the system restore feature restores system settings not application data, so unfortunately, you will not be able to recover the deleted items from the inbox and deleted items folder, unless you have a deleted item retention history policy configured on the back-end. Deleted item retention history allows you to recover deleted items for a specified period of time by clicking tools and selecting recover deleted items from within the deleted items folder. This of course, is assuming that you are using Microsoft Exchange Server on the back-end.