Is it possible to have DHCP turned on on that server and have grey addresses on other two PCs so server can issue 192.168.x.x to those computers?
Of course. I run DHCP on my home machine, but I can’t possible tell you how to configure it, as all home networking devices are different, and I don’t know anything about NAT on FreeBSD (I presume you need NAT?). Webmin’s DHCP module should make things a little easier to manage on that end, however…assuming it’s a DHCP server that Webmin supports.
I am moving from PLESK 8 - it is a very good product
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minuses
Well, we don’t really claim to be cheaper than Plesk, just better. But, Virtualmin GPL is obviously a lot cheaper–can’t get cheaper than free. So, if price is a primary concern Virtualmin GPL can’t be beat. 
Webmin so far pluses
-takes HOURS to tune it.
I suspect this wasn’t intended as a plus?
But, it shouldn’t take any time at all on platforms supported by our installer (FreeBSD is not yet among them, as it is so different from the Linux platforms we support). The install script does everything you need to install Virtualmin, Webmin and Usermin, and configure them with reasonable defaults for web hosting. You, of course, may have a few preferences you’d like to change, but if it’s taking hours, we’ve done something horribly wrong somewhere. I’d love to hear what you’re changing from the defaults, and why, and what we can do to make it quicker.
minuses:
-lack of support (must be GPL thing)
Professional users do get priority in our support queue, and we are, frankly, overwhelmed at the moment–we’ve reached the point where we have too many customers and GPL users to handle them all personally, but we don’t have enough paying users to hire additional support. We’re trying to enable user-to-user support as much as possible (new doc wiki for both Webmin and Virtualmin, these forums, and I’m migrating the FAQ into the wiki as we speak), but it’s a long process.
-some little bits that you have to install yourself (like Sentries, etc.)
Huh? The Sentries have been abandoned by Psionic years ago when the company was acquired by Cisco (I even worked for a couple of years with one of the developers in Austin when he’d moved on to other things–no one had touched the code in well over a year when it was officially abandoned). We don’t really think they are very useful in a modern system. And, of course, much of the functionality that we do think is useful is already available in the Webmin System and Server Status module in a form that’s generally easier to use.
-when migrate from PLESK - webpages, websites aliases (havents checked email aliases yet) and mysql databases don't migrate for some reason (must be bug). Also doesnt support restore of COMPLETE plesk backup - the one that done through console (all sites, databases, etc.)
That’s a bug. File it, provide an example backup file that exhibits this problem, and we’ll fix it. Complaining about it in the forums just “wastes your time and annoys the pig”. 