So you want a column of dates, from which you want a summary of how many fall on each day of the week (2 on Sunday, 3 on Monday, etc.). Is that right? I'm not sure how to go about that. I may look into it later, no promises, but it's getting late tonight.
The second one shouldn't be too hard you just need to enclose your first formula in an IF statement. You select the if-expression variable and tap the cell you are testing then enter ≠0. You then tap the if-true variable and enter your formula. I chose the DATEDIF formula as the easiest way to compute a difference in years. If you need something else to happen when the if-expression is false you would enter it in the place of the if-false variable. Otherwise ignore or delete that part of the function. For the heck of it I entered the string "N/A", so that when there is no entry in field B8, N/A appears in cell E8.
By selecting a calc method of "Y" i get my results in whole years. If B8 is a birthday then E8 will be that person's age as of the current day..
Hold in mind that using the TODAY formula like it did in cell D8 means it is always today. If you want todays date entered, and for it to remain static, you have to enter it manually.
To save a boringly repetitive column you could simply replace the D8 address in the DATEDIF statement with the TODAY function.