> I don't know what the minimum amount of capital that you need to purchase a t-bill

From TreasuryDirect: $100 minimum and $100 intervals.

From a brokerage: Nearly always $1000 minimums and $1000 intervals

Without knowing your income and state of residence, it's hard to answer this question with precision. My suggestion is to use a Tax-Equivalent Yield calculator to compare net yields from different instruments suited to your circumstances. A Treasury Bill may be more valuable if you're in a high income tax state compared to a CD, even if the APY on the CD is higher. Also in-state municipal bonds are potentially tax-free if that's an option.

In this particular case, not really. Admiral shares usually have lower expenses, and this is technically true, as VMRXX has an expense ratio of 0.10% vs. VMFXX's 0.11%. However, within VMRXX, it used to have Investor shares (VMMXX) with an ER of 0.16%. That was phased out a few years ago.

I get you there. Even if you're not spiritual or religious, spending a few moments there you totally and completely understand how these places came to be sacred to the native peoples all over the Southwest.