The economists did all the math, they actually thought of your 1) and 2) and other things besides. (Both the middle and high wage H1-B immigrants helped.)
They usually (not every single time) find that immigrants benefit native workers, that's low, medium, and high skill immigrants. They both increase the number of jobs AND the average wage.
The "abuse" of the H1-B program you mention is also helping even though you are correct that it is against the intent of the program. You almost certainly owe several of your gigs to H1-B immigrants, time when you would have otherwise been on the beach or working at a lower wage.
I know this goes against almost everything you've ever heard. It's counterintuitive. Like treating cancer with radiation, using a back fire to stop a wildfire, or that adding more software devs to a late project will make it later.
You want to look for something like "this poll of economists says that more immigration is bad for the US". "This poll of economics nobel prize winners say that while high skill immigration is good, medium skill immigration is bad". "This survey article of economics immigration articles finds that 70% of papers agree: middle skill immigration lowers wages". You will not find much.
For example these polls of economists say that high skill immigration is super good, but low skill immigration is only pretty good.
http://www.igmchicago.org/surveys/high-skilled-immigrants
http://www.igmchicago.org/surveys/low-skilled-immigrants
As patriotic American who cares for their fellow citizens and also out of self interest you should say "we should really crank up the H1-B program and let a lot more skilled immigrants in".
Also as a rebuttal to your point, the type of economist findings you are referring to are almost always explicitly for complementary labor rather than substitute labor. In the case of H1B abuse, it tends to be the latter rather than the former. Additionally, abuse of the H1B program leads to add-on effects in the labor market that keep salaries low and discourage entry of new American workers - see for example [2].
I want to reiterate that I support the intent of the H1B program and startups using H1B workers are generally doing exactly the right thing. The problem is that the program has been hijacked by corporate interests looking to cut costs and thus it needs to be significantly revised.
[1] https://qz.com/india/1041506/new-data-on-h-1b-visas-show-how...
[2] https://heinonline.org/HOL/LandingPage?handle=hein.journals/...