Microshift shifters bar end shifters are great, I've used them for about 3 years on my touring bike and they work fine, sure you could find better ones like especially the old Suntour Barcon shifters were the best ever made, you can find these on Ebay, or a better modern one than the Microshift would be the Dura Ace bar ends, but do you need something as good as those two shifters? I don't think so. I guess the advantage with the Suntour Barcons is that you could crash on one and it would still work just fine, a modern Microshift or DA would break due to the plastic construction; but the Microshift one is extremely cheap to replace, whereas with the Suntour you might have trouble getting a replacement sent out to you in a one red light town with a tiny bike shop, for that matter even DA would be a tad difficult to get vs the Microshift; plus you're touring, you may be on limited funds, you might not want to spend $50 or more for one barend when you get a Microshift for $25...assuming you can buy just one and not the pair. Just things to consider, and it depends on your personality how you want your equipment to be. I have no problems using Microshift, but should one break I would probably switch over to Suntour since those cost as much as the DA except without all the plastic.
I don't know about the newest Tiagra vs 105, but I did test ride this stuff about 9 years ago and back then there was a difference, the shifting was smoother, faster, and more positive with 105, not to mention being lighter; however, Tiagra, being heavier obviously uses heavier materials that are said to make it more rugged, but I know the bearings and pivots in the derailleur are actually less dependable than 105. However, if you want to run triples the Tiagra is more capable whereas the 105 is not capable. New 105 the idiot engineers used plastic for a pawl inside the rear derailleur, this paw has been breaking, Tiagra does not have that issue.
Personally, I would use Deore instead of Tiagra or 105 for touring purposes, Deore being aimed at the MTB crowd vs the Tiagra aimed at the road crowd, means that the Deore FD T6000 is designed with more robustness to handle rougher situations and survive, as well as to being able to handle triples which I would highly recommend if you are doing loaded touring and expect to be climbing mountain roads, trying to lug 60 or so pounds of gear along with you and the bike up a steep grade using just doubles or a single will fry your legs and or knees.
You don't need a clutch drive for road touring, maybe for off road touring, but the clutch is for doing jumps and keeping the chain taunt while doing very rugged riding and or jumping, a clutch is useless on road touring, so there is no reason in even getting a clutched derailleur if it's not going to be used for the purposes it was intended for. Thousands and thousands of bicycle touring people over decades of time, on road and off road (not rugged offroad), never had any issues with derailleurs that didn't have clutches, and they still don't to this day.