Is the "community property" $1 million (the increase during the
marriage), and does the PP have to give half of it to the RP?
Yes. If $1 million of community property were titled in PP, then PP would owe RP $500K in property division.
Whether or not the answer to the previous question is yes, is the PP
likely to get alimony? And if so, how do the community property
considerations in the previous paragraph affect this?
An award of alimony depends upon the length of the marriage and other circumstances.
One of the circumstances is whether the property division affords each spouse sufficient assets to support themselves. A related circumstance is the amount of income from property that each spouse has available after the property division.
Another factor is a child support award, if applicable (which is usually more fixed in modern times).
Alimony is determined looking at the parties from this baseline foundation (so a modification of either typically requires a revisiting of an alimony award as well).
Originally, alimony who mostly conceptualized as "breach of contract" damages, with the idea being to give a divorcing, not at fault spouse the economic benefit of the bargain of being married for life.
Alimony also embraces the quasi-contract concept of stabilization, i.e. that one spouse should not face impoverishment and a lack of ability to self-support in the foreseeable future. If a spouse, even in a short marriage, has suffered a severe disability, alimony prevents a spouse from leaving the disabled spouse in the lurch and thereby evading a duty of support that would have existed if they had stayed married.
Now, alimony is instead largely conceptualized in part as a remedy for detrimental reliance harm suffered from being married. If a spouse gives up a career to raise children for the couple, for example, alimony remedies the income impairment a spouse suffered, at least in part, from making that choice in reliance on the belief that the marriage would persist.
Another justification for alimony is that marriage enhanced a spouse's capacity to generate a future stream of income even though this hasn't ripened into "birds in the hand" property yet. So, for example, while an educational degree earned while the other spouse put the degree earning spouse through college is usually not considered to be divisible marital property, the increased earning capacity that the degree earning spouse has because the other spouse put them through college is a factor that can be considered in determining what alimony award is allowed and for how long.
The ability of a spouse to pay alimony given the property division and child support award is also considered.
When divorce was rare, alimony was usually the product of a multi-factor test applied by a judge who had vast discretion, at the cost of being highly unpredictable.
Now, in order to reduce uncertainty in an era of massed produced divorces, there is a trend towards having guidelines for alimony based upon the number of years of marriage and the income difference of the spouses, subject to adjustment for good cause in a judge's discretion.
Returning to the facts in the question, if the marriage was short, no one had children during the marriage, and no one impaired their career or had their career substantially enhanced during the marriage (e.g. if RP was age 68 and retired at the time of the marriage, and PP was age 63 in a final few years of a career, and they divorce two years later), it is likely that there will be little or no alimony award.
On the other hand, and alimony award would likely be substantial if a spouse gave up a lucrative career, they had several kids, they were married fifteen years, the spouse with an income had many years of gainful employment left facilitated in part by RP putting PP through college and med school at great expense, and the RP's assets were illiquid and non-income producing assets such as a vested remainder interest in an office building that RP's stepmother had a life estate in.
