You can answer your own question by looking at a chart of indices
...for 4,4 v. 8 for 1 deck H17 NDAS. If you don't have access to such a chart, don't know true count conversion and don't have your indices memorized, I would recommend not playing at all. You are likely to lose, even at single deck. Wendover thrives on such players.
One hand, except in the situations indicated in the link I referred to in my unsatisfactory first answer.
What statistical analysis has been done on this issue?
Plenty. It is not a close call.
I do make sure that the total of hands at the table does not go over 2.
2. What is the recommended bet spread on these one-deck games? On a $25 table, is it $25-$100, $25-$125, or higher?
"Recommended bet spread" is always as big as you can get away with. Higher is better of course.
3. When playing the one-deck game with the rule of 7 with two hands, often the dealer is left with fewer than 10 cards at the end. I do keep track of the running count when playing. Should I make adjustments in the conversion of running count to true count when the deck is mostly depleted? Should I have running count equate to true count for the first half of the deck and then multiply it by 2 during the second half?
That is an easy but adequate method. Experienced single deck players use quarter-decks or rounds dealt, but half-deck will get the money easily.
4. On very rare occasions, I am dealt two 4's and the dealer has a 5 or 6 showing and there being a very high count. Of course no doubling after splitting. In this rare case, should I go ahead and split the 4's or should I double the total of 8.