Your post only serves to prove that GMOs are exactly what people oppose. You mention corporate control of them, and yet, plenty of non-genetically engineered crops varieties are also patented. Besides that, those patents expire, like all patents...Monsanto's first generation of GE soybean is now available as an off patent generic...and you fail to clarify what is wrong with a system whereby one makes something superior, gains control of it for a limited time to recoup their R&D costs, then it falls into the public domain. I can only conclude that corporate control is not the real issue, or else far more than GE crops would be targeted, and the argument would be more coherent.
You then mention herbicides and pesticides. This is actually a great reason to support GE crops. There are no insecticide resistant GE crops, but there are those which resist pests, and therefore need less insecticides. As for herbicides, yes there are herbicide resistant ones, but you neglect to consider the alternatives. Do you think weeds will just go away without herbicides? Nope, but without the GE crops, you have to use harsher types of herbicides, and soil damaging tillage, to control weeds. This argument makes sense only if you know nothing of how agriculture really works. Besides that, there are non-GE crops like the Clearfield lines are also bred to be resistant to herbicides, so even if you had a point, it still would not be a reason to oppose only GE crops as opposed to crop improvement in general. So we can conclude that this justification is also wrong. You may be referring to the recent dicamba problems, which is a real problem, but that is not an issue with the genetics so much with the herbicide formulation.
Finally, you mention issues of saving seeds, which farmers haven't done since the rise of hybrid seed in the 30's. You rarely save seed anymore because it is more profitable to use seed with hybrid vigor, which does not breed true in the second generation. That's not the fault of corporations, that's just how genetics works. Again, if this were the real issue, people would be protesting much more than GE crops, so we can conclude that it is another justification.
Basically, your reasons are invalid. They sound rational enough on the surface, so I can't fault anyone for believing them, but what they really are they are after the fact justifications to make GMO denialism seem somewhat rational to those not well versed in modern agriculture or crop genetics. Keep in mind, these talking points are coming from the same groups that also lie about non-profit, publicly funded projects, like the International Rice Research Institute's Golden Rice, or the University of Hawai'i's Rainbow papaya. Those who lie to you about science will also lie to you about business.