advice asked for the operation of Epson printer

Let me state at the outset that, never so far having possessed one, I am woefully ignorant about the operation of fine art printers.
Still, I want to buy one in order to print large format prints in exhibition quality and digital negatives for alternative processes. I have my eyes on an Epson Stylus 7700 or 7900 - what, by the way, is the practical difference?.
As both would be quite an investment (for me, at least), I need to plan ahead, and therefore have several questions regarding operation:
First, if anyone knows, is this the right choice for printing digital negs?
Second, and no less important, I read that such printers need to be operated on a regular schedules or else the nozzles in the printing head will clog up.
I can't do this. I know there will be times when will use it daily, sometimes weekly or so, but there will also be times when i will be traveling or otherwise preoccupied, and when I will not be able to use the printer at all (easily one or two months at a time).
Now, Epson says about their new models that due to new technology (what else?) "clogged nozzles are virtually eliminated". But still, I would dearly like to know whether there are not procedures of properly setting such a printer up for times of inactivity, so that it can be taken back into operation without too many problems. Running a cleaning fluid through its nozzles? Methanol, perhaps?
Third, I live in Lahore, Pakistan, and it gets quite hot here in the summer - rooms heat up easily to more than 40°C/ 104°F. Humidity stays in the room at about 55-60, in the Monsoon it goes easily up to 70.
When I run the printer, I will of course do so with an AC during the hot season, but to run one continuously is forbiddingly expensive - apart from that I think the resulting drop in humidity would create more problems with clogging than solve.
If you have any other advices concerning the operation of such a printer, I would also dearly like to know them, as I should know what I'll be doing.
Lukas