<--- To be fair, I *am* jesus

But those ideas would suck in NS, sorry.
It's a good principle, but having your marines that close to the hive, I would rather set up a PG and siege/sg rush than place a few mines to deter them.
The principle is sound, box in the aliens so you don't *need* to defend your base, however in reality things do not ever turn out the way you expect them to. Like it or not you *will* get skulks harassing your base, and no matter how many mines you drop they will find a way in.
The point is that when they do appear in your base, you wait for a marine to spawn, then jump out of the com chair at the same time and both start firing at the skulk(s).
The skulk then has 3 choices:
1) Continue trying to kill the structure it's biting (if it is biting one)
Advantages - If building is on low HP it could take out a critical building like an early adv. armory or arms lab.
Disadvantages - Ridiculously likely to get shot to hell.
2)Attack the marines
Advantages - If he's a very good skulk, or against very inept marines, he could take them both out, and possibly camp the IP(s) and/or kill a critical building
Disadvantages - He's also very likely to get the crap shot out of him as he tries to close to biting range (you put the IP's as far as physically possible away from the CC, right?).
He might get the guy who just spawned, but the com should be that distance again, away from the IP. If you cant shoot a lone, wounded skulk at that range you deserve to die.
Also, while the skulk is attempting to close the range to bite the marine, he's gonna have to be dodging mines, because you planted mines around the IP and other critical buildings (adv armory, arms lab) remember?
3) Run like hell
Advantages - Might avoid giving the marines some RFK.... *might*
Disadvantages - Is more likely to die than do anything remotely useful, at best he will escape wounded, have to return to the hive for healing and that will be almsot as bad as waiting in the spawn queue.
So, in effect, the economic use of mines in certain effective places (around IP, around adv armory/arms lab, a few between arms lab/adv armory and IP) can turn an otherwise idyllic place for a skulk to spawn camp, into a deadly killing ground where a skulk suddenly has to worry about 12 things (spawning marine, com, 10 mines) killing him.
All at once.
The point is not to make your base impregnable. Because that's playing defensively. If you com defensively you *will* lose. The single best way to defend your base is to make the skulks need to go elsewhere, be it a hive under attack, a series of RT's getting owned.