None of the items you mentioned are the "wrong decision", they are all good things. Some of them might be less optimal than others, but you're in a good position to start really building up investments.
The very last thing you need is more equity in your house. With an interest rate under 3% I wouldn't pay a dime more than required. Eventually you might want to consider cashing out of that house and investing that $550K equity into something that makes you some money, but that's a hard step for most people so take your time.
If you can get the money out of your 401K and into an IRA, there are many place to invest it that will have low fees. The questions is, can you get the money out of your 401K? Many times this requires leaving your job. Sometimes plans allow for in service distributions. Talk to your HR department to find out.
If you're going to do a Roth, do it through Vanguard not first investors.
Since your immediate goal is to fund college tuition you should do either the 529 plan, Roths, or both. Roth's have income limitations, but you can do a backdoor Roth if you make too much money. Many 529 plans have somewhat limited investment options, so check into that when setting it up. 529 plans also must be spent on tuition, so if all 3 get scholarships or don't go to college you would have to either pay a 10% penalty to get the funds out, or transfer them to another beneficiary.