Loud: Yep, it is noticeably louder than our regular kitchen fridge. I have it sitting on a thick rug which definitely helps - when I first got it we had it on the linoleum in the kitchen, waaay too much sound. It definitely isn't going to sit next to your TV if that's what you're thinking. I DO believe the condenser fan could be changed out for a quieter one - that's where 80% of the noise comes from. The compressor itself isn't particularly loud. I kinda started looking around for alternative condenser fans but it just hasn't been a big enough problem for me to bother as the kegerator lives in our "other" living room as opposed to the "family room" where we spend most of our time.
Power: It costs about $12/month to run. No brainer compared to the cost of buying beer! Absolute PEAK energy use (at startup) is about 8A, so be mindful of what else is plugged in to the circuit. IE don't share with your space heater, and for your computer's sake don't share with it either.
The height works fine, mine is 25" internally as well. The low profile couplers actually don't project past the top of the keg (the rim of the keg is taller than the coupler). Yep, it is tight but I think this is actually the application those low profile couplers were designed for. There are hundreds of thousands of these fridges out there (or their competitors) and the size is common across all of them. 25" high internally, 27" wide externally. I think Perlick saw that a lot of folks needed a solution to fitting a keg in a standard commercial kitchen fridge and designed the couplers accordingly.
Mine is a SKRB27 - similar, but mine is a front breather (meaning it can be completely enclosed, it pulls its fresh air in the front on the right side and exhausts hot air in the front on the left side). The one you are looking at has a rear condenser more like a "normal" fridge - if you ever build it in to a bar it will need to have ventilation in the back. I see it actually has a smaller condenser fan than mine does - yours is using the same fan for the condenser as mine uses for the evaporator inside. My evaporator fan isn't particularly loud, I mean there is a whine for sure, but it isn't anywhere near as loud as my condenser fan. Good chance that one will make less noise.