I'm currently a software tester at Microsoft, and recently was promoted into the senior band. I'll comment on some of your points, to offer my contrasting experience.
1. this has never happened to me in my career. The spectrum of responses I get from developers are "why are you bothering me with this" to genuine appreciation. I am not discounting your experience, but know that you were probably in a defective org. They exist, but they are not the rule.
2. Nobody questions my competence after working with me. Also, if what you do doesn't impact the product, you definitely shouldn't be getting promoted. One of the factors mentioned in my reviews is the impact I continue to have on features and design decisions.
3. This is somewhat true. The SDET role was unique to Microsoft for a long time, and originally it was basically a ramp-up period to landing a dev job. The idea that a tester would want to continue to test (instead of moving into product development) after showing the competency and value required for several promotions just wasn't something Microsoft ever planned for.
The result is that Microsoft is struggling to define what makes someone clearly a Senior or Principal level contributor in a test role. This is doubly (or quadruply?) true if you are not currently or aiming to be a manager.
4. If it's any consolation, managers lie to other managers, managers lie to developers, and managers lie to PMs also. Management and lying are just part of how it works :)
5. Not true at all in my org. I've had developers buy me lunch before because I was able to help them find bugs we all knew were in there but they couldn't successfully track down.
6. This can certainly happen. Your job (and what makes you stand out from the other testers) are figuring out what to do about it. Do you refactor your tests to better insulate them from that kind of thing in the future? Do you attend or get feedback from dev meetings and offer estimates of test impact to proposed changes? Do you help make the schedule accomodate test constraints? Do you make the case that you need more help, perhaps some vendors to get through things? Do you show how you can deliver the same risk containment with fewer active tests?
The difference between career band N and career band N+1 is expanding the number of hardships you can turn into opportunities to demonstrate personal excellence and deliver team results.
7. So don't do manual testing. __Exploratory__ testing is where the majority of bugs are found, especially in actively developed areas of the product, and for many problem types is the most efficient activity in terms of hours spent vs. defects found. Exploratory testing is also one of the best ways to become domain experts on the product, and makes the automation you write considerably more effective. Read up on "exploratory testing" if you haven't -- it's what people _should_ be doing when someone says "manual" testing. At this point I relegate the definition of "manual testing" to following a script that has been prepared in advance and will not be deviated from. This sort of manual test is something that has enough value to be done more than once but not enough value to be automated (right now).
8. This is probably true. I've interviewed with other companies and they don't quite know what to do with me. Most people don't realize that SDETs were typically developers in their previous careers. I was a UNIX C++ developer prior to working at Microsoft. Seeing "Microsoft" on a resume can help get you noticed but seeing "10 years doing testing" is a hinderance. Like most jobs, you really need a referral or an inside-advocate to get your foot in the door. Once you have an opportunity to talk about what you've actually done with someone who understands software, it's less of a problem.
Personally, it's something I enjoy doing and am good at. There are aspects of the job (and the company) that upset me, but the developers on my team get upset by a lot of the same things.
The world is starting to learn that professional software testing is its own animal, with a different set of competencies.