You are welcome. I think you have a very common and understandable fear about a sudden crash. Throwing in 20% bonds would help protect against a sudden crash. But it won't eliminate it. The problem with protecting against crashes is that it is really hard to do it right.
1) You need to recognize the crash early, but not pull the protection trigger on the numerous false crashes that regularly occur.
2) You need to wait out the crash and don't just jump back in as it is still falling.
3) You need to recognize that the crash is over before other people do.
4) You need the confidence to get back in before it rises again.
You might do well on one or two of those tasks. But can you do all 4? It is all or nothing, otherwise your protection will fail you.
Instead of worrying about crashes, try to embrace them. If you put in your max $5500 for 2017 and the market crashes to half its value the next day, you are out $2750. Sounds horrible. But, in the scheme of your retirement, a temporary $2750 loss on paper is nothing out of the millions of dollars that you intend to get by the time you retire.
Instead, that 50% stock market crash is a buying opportunity for you. Yes, you lost $2750. But, if you put your next year 2018 $5500 into it, then the stock market doubles to return to where it started, you just made your $2750 back on your 2017 chunk AND $5500 on your 2018 chunk. Total gain: $5500 on that stock market crash just buy buying regularly and holding. Since you are young a crash is the best thing possible for you (assuming it isn't such a bad crash that you lose your job).
If you are still worried about an imminent crash, then put $500 in a month (assuming you can with your brokerage) rather than $5500 in all at once. That way, you max loss is very small if it crashes right away.
I personally would not worry about crashes when starting out. Your balance is just too small. A paper crash when you have a few thousand dollars is painful, but meaningless. A crash when you are retired with millions of dollars is vitally important. Worry about crashes then when you are experienced and have something real to protect.
I do not know enough to answer you there.
What you are missing is that gold has a massive peak in value every 30 to 50 years, then it plunges in value every 30 to 50 years (it happened in the great depression, the 1980s, and now the 2010s). That 10 year trend included one peak. If history repeats itself, that 10 year trend won't happen again for many years.
I see nothing particularly wrong with that concept. But you can rebalance yourself without paying a fee (note: frequent trading in a retirement account is frowned on, so monthly might get you into trouble). Also, stock market trends tend to last a couple of years. A particular stock, may rise continually for a few years, then drop for a few years. With monthly rebalancing you will be guaranteed to be selling that rising stock just as it starts to rise (missing out on the whole rise) and buying a clunker just as it starts to fall (getting the full fall). There is no right rebalancing period, but annual rebalancing or rebalancing when things are significantly out of whack is often suggested as it is simple, easy, and generally near the max return and minimum volatility (risk). Here is a paper, on page 8, where annual rebalancing had higher returns and less risk than monthly rebalancing:
https://www.vanguard.com/pdf/icrpr.pdf Note too that no rebalancing at all had even higher returns, but the volatility (risk) was way worse with the no rebalancing method.
I think that is a perfectly fine distribution. But, as you just starting out trying to get 0.5% or 0.8% of a tiny contribution seems to be a lot of effort for no real benefit. For example, 0.5% cash of your max $5500 IRA contribution is $27.50 in cash. It just seems pointless at the start to hold just $27.50 as a cash "investment".