The only advise I can really give you is to plan WAY ahead, as in if you think it will take you 3 hours to make this, plan to set 6 hours aside instead.
Clean up after yourself every step of the way, this will make things SO much easier for you in the long run!
I would cut the cake into 4 sections before cutting them in half and filling them, but that just seems like it would be easier for me.
Refrigerate everything along the way, nothing is more frustrating than trying to work with icing that is drooping down the sides of the cake.
For more cake ideas, please see the posts in my group:
http://teamsugar.com/group/212775 :shamelessgrouppimping:

When you ice the blocks.. first do a layer of really thin icing. So thin that you can even see the cake through it a little bit. Then stick them in the fridge for awhile until that icing is hard. Then when you ice the cake you won't get crumbs in your cake and the cut sides will be so much easier to ice!

One word ... FONDANT. Im in love with this stuff ... google it and you will what I mean!