Hi Ashish, on question 2, it sounds like you have a date locale mismatch. 1-7-2018 could be either January 7 or July 1, depending on your locale settings. If you select July 2nd, I'd wager you will see February 7th, instead of January. I recommend checking the locale settings on your Server to make sure they match the computer where you are using Tableau Desktop.
Hi Chang, Appreciate the response ... I doubt if it's something to do with locale settings, as the issue is coming up only when using date parameter ... when I use the date dimension it works just fine. But yes issue 1 of month drop down not showing up persists in both cases ... parameter or date dimension.