Several hours ago, I posted to the the Vanguards forum with no responses so far. Perhaps that was the wrong forum, so I hope you folks here can steer me in the right direction with some income-stream questions concerning bonds.

My wife & I are very conservative with our finances, and we are inclined to use a "buckets" strategy" for our retirement years in which an "income bucket," consisting of 2/3s of our total portfolio, would generate enough income to spin out a withdrawal rate of ~2.8% of total portfolio. This income would be combined with a State of Fla pension, social security, and perhaps an annuitized portion of our TIAA-CREF holdings. Using this withdrawal rate,  it appears that we may be able to leave a nice estate for our two sons, but a major variable we still need to nail down soon is long-term care insurance (eg whether to attempt to self-insure, not the subject of this thread).

I am beginning to consider whether to recommend to my wife that we purchase individual bonds for part of the "income bucket" and part of our retirement income stream. I understand a basic benefit of directly holding the bonds til maturity is to obtain a predictable income stream but I also understand some risks involved, eg corporate bonds' call and credit risks. I also intend to re-read substantial potions of Swedroe's ...Winning Bond... book and to read it more attentively this time.

At this juncture, three questions I hope you can help w/.

1. Have there been studies I could read on income-stream portfolios comparing streams and outcomes of (a) directly owning bonds vs (b) bond mutual funds vs (c) laddered CDs, or (d) combinations of these?

 2. What are options for safe and low-cost ways to buy and hold (and if necessary, sell)  individual corporate bonds? Eg, I glanced at USAA's brokerage web page, which shows  fees at "$25 + $3 per bond" for "Listed Corporate Bonds." Are these fees competitive? Better options?

3. If we decide to purchase treasuries, I do have a Treasury Direct account already with a substantial position in Series I bonds and have noticed the option to buy bills, notes, and bonds through that account. Better to buy through "noncompetitive bid" or "competitive bid"?

Any thoughts or comments on any of the above, appreciated. 

TIA, Steve