Speaking as an occasional male Viagra user, here's some notes which might include field reports... :)
According to some chums and my personal experience, Viagra is an assistant, and not the tool. In other words, it helps one gain an erection, it doesn't do it for you, so the regular steps one would take toward that still need to be taken. Yes. Foreplay. For everyone I know of who's used it, it doesn't give the patient an instant erection and keep it for the next 4-8 hours, one still needs to work at it a little...
Eating lightly, and perhaps even more importantly, drinking a large glass of water or two definitely helps the digestion of the treatment, gels are better, faster dissolving.
Overdoing the alcohol isn't a great idea and yes, delayed orgasm or inability to reach orgasm can easily happen - one pal had this problem so he halved his dose by the highly technical method of cutting his tablet in half and it worked wonders.
And yes, datenight is a great plan and as mentioned above, keep reminding each other about the plan.
Also, one can buy variations of Viagra online if ones partner doesn't want / too embarrassed to go to the doctor, or even if you just want some to liven up a naughty weekend away. I won't post links, but feel free to pm me.
Lastly, well done to you OP and to hubby, after all that time taking the steps to resolve the issue, good on you, and surely after an extended time of no great success, it'll take a few go's to get back into the correct rhythm won't it? Good luck :)