Walk me through buying 50k in BC using cash in Dallas and exchanging BC for cash in the SF bay area 3 days later. Specifically with attention to costs and fees, and maintaining anonymity via in person transactions or whatever method is most relevant to maintaining anonymity.
for cash means you want paper then it is possible only theoretically - you sell it in the same way as cucumbers or gas to the people that want to buy it. You just need to find them and it will be hard because if you don't want to do it online means you are afraid of something: fake banknotes, money laundering, etc.
Finding an Exchange
I'm not sure if there are walk-in exchanges in Dallas, but the Bitcoin site is a good place to start a search. Most exchanges take a couple of days to set up and verify your account, so just walking in and purchasing $50k of Bitcoin is unlikely.
Your specific fees will depend on the exchange that you choose. Generally you should plan on the purchase costing around $1k. You shouldn't have any fees associated with selling, apart from the transaction fee, which should be less than $30.
When Bitcoin began it offered a great deal of anonymity, as there was very little regulation. It's use as the primary currency for illegitimate transactions on sites such as Silk Road has brough regulation which errodes anonymity. Now exchanges will require photo identification (not uncommon for them to ask for more than one form as well) prior to doing business with you.
Hypothetically speaking, I believe its still possible to use Bitcoin with some anonymity. Its unrealistic to think that you'll be able to achieve this with a quick $50k cash transaction. If anonymity is important, you may have a look into Monero.
If you're planning to use Bitcoin specifically to transfer funds, then you'll need to be aware of volatility. There are many speculative traders betting for or against the Bitcoin, which means that the price can (and does) move rapidly. 10% movement in a day isn't uncommon. The longer it takes you to sell your coins, the less likely it is that they'll be worth the same amount you paid. For the amount that you're asking about, you could easily lose or make a few thousand dollars in 3 days.