It all depends on what network you are on. Networks are not all the same. For example, some networks have chanserv, which will allow you to always maintain your op status even if you leave the channel. Other networks have something similar that can provide the same service.
Others don't have anything to do that and your only way to maintain ops would be to have other ops (or bots) in the channel with you so that they will always op you again if you leave. Of course, if all the ops leave, no one can regain ops unless you get everyone to leave the channel so you can rejoin and regain ops. In those cases, the first person to join an empty channel will be an op no matter what.
If you are looking to start just a small channel and do not want to have about 5 ops (you need that many to help prevent you from all being offline at the same time and losing ops), then I'd suggest that you choose a network that has chanserv. With that, only you and whomever you choose will ever have ops in your channel because chanserv will handle it for you.
As for commands, many are built right into Invision if you right click on someone's name.
Some basic commands are:
(+ adds a mode and - takes it away, so +o is op and -o is deop. This is true for all modes)
OP/DEOP:
/mode #channel +o nick
/mode #channel -o nick
VOICE/DEVOICE:
/mode #channel +v nick
/mode #channel -v nick
nick!identd@host.com can be formatted as you wish... the more precise you are, the less likely you'll ban more than the person you're trying to ban, but it is also easier for that person to avoid the ban. For example, if I banned Riamus!*@*, then no one using that nick could join the channel, no matter what host they are on... but the person could just change the nick to something else and join. This is useful, however, for preventing certain nicks like Guest nicks from being in the channel. Remember that * means it can include anything in that location (any number of characters).
BAN:
/ban nick!identd@host.com
KICK:
/kick #channel nick reason
For more help, you should join the #help channel on whatever network you choose to use. They will be able to tell you what you need to know about starting a new channel. Remember that if you have chanserv and/or nickserv on the network, you can also type /nickserv help or /chanserv help to see how to use those commands.