But even if legally I'm okay, I wonder if the company will hate me...
Whether they hate you or not, I suspect that filing this patent application will jeopardize your employment. They likely extended an offer to you based on the expertise you demonstrated relating to a product that they want to develop and market. From what you have written, it appears that protecting what you consider your IP will also encumber that expertise, which may mean you are no longer worth the compensation that they offered. In practical terms, what are you going to do? Refuse tasks that you consider to be infringing? Make threats if you observe coworkers designing/coding using 'your' IP?
...if I later disclose it to them...
If they are a Dow 30 company, I expect that their patent lawyers are monitoring filings around all technologies of interest, and it won't take them long to connect the dots. They will have figured out what they want to do about you well before you report for your first workday.
...license it/or partner with them...
In my experience, corporations have employees, and they have partners, but never the same persons.
Also note that, separate from the IP agreement, there will probably also be an agreement to comply with all policies and procedures in your Employee Handbook (or some such). In general, Rule #1 is "don't do anything that is not in the Company's best interests." If there is a Conflict of Interest section, that Rule #1 is "don't compete with the Company." (One such agreement I'm familiar with prohibited employees from owning stock in any companies that were considered competitors.) Soliciting funds on Kickstarter to protect/promote/develop your IP could be considered as competition.
Your specific circumstances may render the above null and void - perhaps the Company considers you a purple unicorn and will accommodate your demands (which is why I used plenty of weasel words rather than making definitive assertions). But I haven't read any such indications. In addition to talking to IP experts, I suggest that you seek out some profs (with industry experience) in the business school and ask them whether they think your Dow 30 company will play ball with you if you file.