The funny LF tendon/pastern may just be a ridge of long hair, can't tell from the photo. I am not particularly impressed with the conformation but if you just want a backyard horse to plunk around with it doesn't necessarily matter that much (except insofar as it affects how easy she is to sell later on, if it should become necessary or desirable).
Youngsters need safer fences/sheds/etc because they are more active and find more ways to hurt themselves (and because they have smaller body parts to stick into smaller crevices). What is your fencing like?
Also, because young horses are usually more active and silly, there is a good chance your footing will get ripped up more when it is soft or muddy than you'd expect based on what you see from your more-senior-age horses. This is not a problem necessarily -- I only mention it because you were asking about differences to expect.
The biggest potential difference is that she is a "she" and they are "he"s. Many times, geldings can live peaceably with a mare, but a significant number of other times it'll cause trouble. Either because of her behavior when she's in heat (some mares are extremely witchy, others get downright aggressive in their attempts to get someone to breed them), or because one gelding decides she is His Exclusive Girlfriend and goes after his male competition, or other similar problems. Unfortunately there is no really good way of knowing whether these sorts of things will happen in any particular case. You would want to have a Plan B in mind in case it should turn out that she cannot live with one or both of the geldings for some or all of the time; although it is certainly possible the Plan B would not turn out to be necessary.
BTW, if you do have access to appropriate help when needed and do decide to get a youngster, for heaven's sake make sure it LEADS REAL WELL when you buy it. Otherwise you start out with problems right from time zero and that doesn't lead anywhere good.
Good luck,
Pat