$7,000 invested in Vanguard Total Stock Market ETF would be at 0.05% annual fee, or $3.50/year. An institutional version might cost $1/year, saving you $2.50/year. Given the level of savings is so small, you might put more value on being able to select funds.
I'd favor a rollover at Vanguard, and then converting into a Roth IRA. After your standard deduction / standard exemption you're only being taxed on $32k/year, less your 401(k) contributions making it about $25k/year. In the 15% tax bracket it's very appealing to lock that rate in, and convert to a Roth IRA. Your income could go up in the future, and taxes in general could go up. So a Roth IRA removes uncertainty and probably does better than your future tax rates.
So my suggestion would be to do this in two steps: first, have Vanguard transfer your old 401(k) into a Traditional IRA. That means pre-tax money arrives at Vanguard as pre-tax money. Then once it's at Vanguard, you can make a Roth conversion online (or call Vanguard if you prefer, or mail the forms). You will owe just over $1k tax on your $7k Roth conversion in the 15% tax bracket.