Well, slightly off topic.. Well slantways.. A normal squadron should have different types of ships like a navy fleet..
Actually, not really. The original meaning of the word was a small force of a single type - typically a squadron of destroyers (Russians still call destroyers "squadronships", even though they have not been really operated in squadrons since the fifties), perhaps a squadron of battleships.
Or, to be more specific, this was the meaning of the word in the World Wars, which arguably would be where the jargon of Trek derives from. Before that, squadron was just how you hacked a fleet into smaller pieces - but since a sailing fleet would consist purely of ships of the line (the exact class not being a particularly relevant concept back then yet), it's close to the WWI/II meaning of the word in the end.
Since this is the first time we hear the term used in Star Trek, as opposed to the preceding Fleets and Task Forces, we might just as well assume there's a distinction. And it could be exactly this: for a Task you send a mixed, well thought out Task Force, but for an impromptu sortie like this you send a Squadron of Inquiry class ships only, all of them sailing from the Inquiry class pier at Sol or something.
Never should a ship be "the only ship in the sector!" Even long range exploritiry should have at least a few ships going in the same direction and be able to help in emergencys
Well, our heroes used to be the only ones in the "quadrant", which evidently was smaller than a sector (the name would suggest one-quarter the size, but how do you split a cube in four parts?). Although there did seem to be a bit of a starship vacuum around Earth specifically - perhaps because all those ships were needed farther out, and it was inconceivable that a foe could penetrate all the way to Earth without going through those ships first. Until a foe fast enough or unstoppable enough came about...
Timo Saloniemi