As per BOD, the answer to the first question is, "yes and no," in a way that ties into the second question. ASSJ gives you a 1.5x multiplier to the SSJ boost, and USSJ doubles the boost. In addition, both in theory raise the base power cap to 375 million, just like FPSSJ. However, they get slammed with diminishing returns far earlier and far harder, and also give no endurance benefit like the mastered form does. So it would take a lifetime to grind them up to a comparable or greater power level -- as House Talt discovered while trying to find a way to master them. That said, a FPSSJ who tried to bulk up would simply go USSJ, doubling their 750 million boost and arriving at a total transformed power of 1.875
billion, but with all of the crushing endurance and speed penalties of the bulked up forms. So if you've got a
really big blast that needs charging, and absolutely nothing else, it's the superior form. Thus, under the right circumstances and used by the right person, USSJ is stronger in terms of brute force, yes.
And as
@Aranfan pointed out above, the implication is that that power level is equal to SSJ2. And under the BOD system, they're correct -- SSJ2 kicks up the boost from SSJ by a factor of 2, but with an equivalent proportion of endurance and speed to a normal Super Saiyan. So a Full-Powered Super Saiyan who bulked up into USSJ and got into a beam struggle could fight a Super Saiyan 2 on equal ground -- for like a minute, until their ki ran out. And then they would be vapor. Really, really buff vapor.
No worries! Welcome back!