Withholding after working part year and then retiring

So my wife and I retired her in Mar. and me in May. Now that we are retired we have income from a State retirement plan and SS. 

 

1)I do not want to get hit with a fine from the IRS for not withholding enough. I am having Single 1 with held from my state pension.  How can I check that is enough?

 

2) My employer's 457 and 401B lost significant amouts this year and I rolled them both over to my 401K directly, how does that loss show up?  

 

3) Any advive on how/when to roll some of my 401K into a Roth.....I am thinking next year when are incomes on truly lower?

 

Thanks for any advice you can give me. I know this is ballpark as I don't feel comfortable listing amount of $. but we are a middle class level.

Ed