If I was to set up a Roth IRA, say, in a T. Rowe Price mutual fund, could I pull that out and put it directly into, for example, a Fidelity mutual fund without penalty?

You may want to check with the fund to determine if early redemption fees would apply. Excluding early redemption fees, set up fees and the like, no penalty would apply for a trustee-to-trustee non-reportable transfer. .