Let me answer you straight.
Re:side skirt, early M1 tanks (including early versions of the M1A1) had the last part of the side skirt removed by the crew because they tend to get torn up or damaged by the track. The round cover on the sprocket wheel is a track guard or something like that which IIRC ensures that the track doesn't get removed from the sprocket. Or something to that effect. All this was remedied with later versions of the M1A1-HA/HC when some additional structure - forgot what it was called - was placed to strengthen the rear because of the additional weight of the HA/HC versions of the M1A1. The Tamiya kit offers the old style 'smiley' tracks. If you're building it as ODS version, that'd be appropriate. Newer tracks (as such offered in Trumpeter and Dragon kits) have larger track pads which are replaceable. The new track was used because the additional weight reduced the lifespan of the old smiley tracks. The newer ones can be easier maintained by replacing the rubber pads. So, you could do either, but with preferably, do the one with the square end and with the guard in place - more accurate to depict an early M1.
The duct tape has probably 2 purposes - 1) to secure the MILES strap - maybe the velcro wasn't working and/or 2) as an ID feature - something like the thermal ID panels used in this current war.
As Sabot said, the Tamiya M1 (as well as the Academy M1) is good for early M1 versions because of the tracks and other kit parts. If you want a more current M1A1, get Trumpeter or DML/Dragon - they have the newer tracks.
If you have more M1 questions - especially field use, etc. - try out
www.tank-net.org, head to the Armor forum, and post a thread. That site has gots veterans that have driven the M1 in ODS. They provided some of the info I just placed above. Also, for more pictures of the M1, head to
www.armorinaction.com by Scott Cunningham, M1 tanker and also member of TankNet. The site has gots lots - and I mean a LOT - of pics of M1s in the field - from Europe to ODS to NTC.
Hope this helps.
