mongoct's advice is all good. One thing that could be added -- so I shall add it -- is that the two major Japanese rivals, Toto and Inax, both make adapters for their toilets that allow the same toilet to fit securely in spaces that have rough-ins ranging from 10" to 14". (Some users have said that, at the extremes of the adapter, the flush may be a bit louder due to the extra piping between the toilet's trapway and the drain, but -- apparently -- flushing performance is not adversely affected.)

This may seem simplistic, but turn the water off to the tank and flush it twice, first will empty the tank, second will allow most of the water to drain from the bowl, what is left in the bowl can be soaked up with paper towels or rags compressed into the bottom of the bowl. Because of the danger of methane gas seeping back into the room through the empty trap in the toilet. Leave the paper towels or rags in place as a stopper or blockage to prevent the gas seepage, or simply leave the water in the bowl to prevent the gas from seeping back in. If all of the water evaporates you will have to stuff something in the bowl anyway until you can have it replaced. When replacing the bowl you will also want to use some wadding to block the drain line while working on the replacement to prevent the gas. Not only does this sewer gas cause an unpleasant smell but can be dangerous if allowed to build up.

6 flushes/person-day x 4 persons = 24 flushes/day 3 gallons/flush saving by using 1.6 toilet x 24 flushes/day = 72 gallons/day saving by using 1.6 toilet $8/1000gallons (water-sewage rate) x 72 gallons/day x 365 days/year = $210/year saving by using 1.6 toilet $300/1.6 toilet x 3 toilets = $900 to replace w/ 1.6 toilet Payback time: ($900 to replace w/ 1.6 toilet)/$210/year saving by using 1.6 toilet = 4.3 years Typically, if the payback time is more than 3 years, it is not considered to be cost-effective. I will wait on the replacement.

The faucet and dispenser holes are filled with scraps from the cut-out. This is a job I did last week; removing a failed polyester bowl from a polyester solid surface top and replacing it with a stainless steel sink. No countertops were removed in the process. It isn't that much different with stone, the trick is making sure the footprint of the replacement is identical to or larger than that of the original. I've had budget-conscious clients that didn't care that the negative reveals were off on their replacement sinks in stone. Sink, faucet, soap dispenser, and disposal replacement, plumbing, top refinish and cleanup (ooo..it's messy) just over 3K. That's a Mirabelle sink made in Vietnam. Nice.