Would Alt-Clark risk canon dimension to save Lois? Um, yes. Personally, even though we always perceive Lois as the impulsive one in their dynamic relationship, I think Clark is just as impulsive and sometimes irrational (the "it's-for-your-own-good" argument is a good example of that). We only met Alt-Clark a couple of times, as did Canon Lois, but it's obvious to everyone that he was already in love with her. I'm under the impression that he'd risk it for even a slim chance at getting Lois.
Two problems come with that, though. The first being that the Alt-Lois he is rescuing may not in fact be the Lois he loves (
what? yes. I went there.) Maybe she will be different, or never love him back, as described in the numerous scenarios listed in question three. But again, I don't think Alt-Clark would consider any of those factors. In fact, I don't think he would overthink it at all. Clark might, but Alt-Clark had different experiences. Also, I think the way he became Superman changes how he would react, as well- the whole world knowing he's Clark Kent and Superman might take some of the fear and pressure off. He'd know how to handle it better.
BTW, this is presuming that time hasn't gone by too much.
The other (unmentioned) issue- and what I consider the more relevant one- is the risk it brings to his own Alt-dimension. I agree with Lynn that someway, somehow, HG Wells would figure out a way to fix canon universe. I mean, the guy's got plenty of time on his hands. He'd figure it out. But the revival of alt-Lois in her own world I think would cause more issues. When would he return her? To his own time? After she'd been missing all that time? How would that reflect on his Superman personna? Or would it cause some sort of universal upheaval (worst-case scenario)? And if not to his time, then when? To the time when she first disappeared? That would bring the canon universe into jeopardy more than anything else. Besides that, Alt-Clark would not (likely) get the chance to relive time, so he'd had to have wait to find Lois in his own time, oblivious that he simultaneously screwed up his own history and the creation of Superman.
Alternately, if returning Alt-Lois rewrote time, then it would provide the opportunity for both the alt and canon universes to cross paths and coincide- their pasts being the only exception (i.e. Alt-Clark's parents would still be dead).
All in all, I think Alt-Clark would still do it. Despite all the reasons not to and the fact that he could be destroying two universes by doing so.
