Bus for Mishima to Kawaguchoko

I would like to travel from Kyoto to Kawaguchiko using your former answer and taking a bus from mishima. do I need to reserve places on thar bus? how do I do it? is it possible to travel on thar bus with suitcases?

Use google translate.
http://bus.fujikyu.co.jp/rosen/detail/id/6
With 特予(Exp+reserved) are only need booking before
(no online sale/if not full no reservtion traveler possible)
and using Expway bus(one door) type via expway seat numbers about 50.
http://userdisk.webry.biglobe.ne.jp/024/407/36/N000/000/000/1393767406...
With double circle[◎] operate Sat/Sun/ntl holidays and high season(in GW and more) only.

Other bus are using regular type bus no via expway paying by IC card possible.
http://urx.nu/iM00
http://bus.fujikyu.co.jp/rosen/get-on-bus
http://bus.fujikyu.co.jp/other/pasmo (ICOCA,too)

Thank you for your respond.
Is it possible to board with suitcases?

All expway(Japanese calling "Highway") type bus in Japan with a large trunk space under floor.
http://blog-imgs-62.fc2.com/k/a/n/kanto2525ohta/IMG_0093_2013091615384...
But most regular type bus in japan no space/rack for big luggage usual. (cycle rack,too)
http://www.city.yokohama.lg.jp/koutuu/kigyo/newstopics/2013/topics/img...
http://halfzero.sakura.ne.jp/upld/img/img20130923174904.jpg

Special colored or faced for passage are priority seats.
http://userdisk.webry.biglobe.ne.jp/004/511/62/N000/000/009/1345704288...

So in ur case book a Expway type bus comfortable.

And forgot at last about info of
over night(via Expway) bus "Fujiyama liner[フジヤマライナー]"
from Osaka[大阪]/Kyoto(JR Kyoto stn[京都駅]) to Kawaguchiko direct exist.
http://bus.fujikyu.co.jp/highway/detail/id/9
http://www.kintetsu-bus.co.jp/highway/routelist/route_detail.php?no=14
Need booking before. Two bus company sharing operated.