We are planning to arrive kansai airport around 1-2pm on 12th of April Arriving so early, you can visit a Ticket Pia shop in KIX airport, though this may make it harder to "give him a surprise."
It's not clear whether tickets for a show by Osaka-Prowres / Dragon Gate are also sold at a Ticket Pia shop, but it seems Pia is designated by each of the two organizations.
The shop is in the north half of 1F (= arrival floor for those after international flights) and open from 10 am to 8 pm every day. Probably you will find a logo of Ticket Pia shown in this image:
http://www.pia.co.jp/pia/service/ticket/images/new_ticketpia_logo_2010...[Osaka-Prowres]
According to the website linked to by thecobra2,
only tickets for seats without reservation can be purchased through Ticket Pia,
and this means those hoping to watch a show have to get numbered cards in advance on that day at Osaka-Prowres Goods Shop (on the 1F of the Arena), which are available
from 1:00 pm on Wednesdays and Fridays,
from 10:00 am on Thursdays, Sundays and Tuesdays,
and from 12:00 on Saturdays.
It is estimated as about 40 minutes from Shin-Osaka Station Hotel to the Arena,
which is about 15 minutes to walk to subway Shin-Osaka Station and wait + about 10 to 15 minutes for a ride + about 10 minutes from Namba Station.
(By the way, "honkan" means a main building.)
In Namba Station you can find an escalator labeled "D" at the platform's end in the direction of Shin-Osaka, which will lead you to the upper floor. Turning right, you will see a ticket gate. Feel free to ask the station's staff how to get to the Arena, which the website says is near B20 and B22 exits of Namba Walk underground mall.
[Dragon Gate]
we are staying at shin osaka honkan station hotel, and we have jr west pass, will we be able to go there and buy the tickets in advance? Do you have San'yo Area Pass or Kansai Area Pass? Anyway, I suppose your pass will not save much money as to some possible routes between Shin-Osaka and Takaishi Stations.
e.g.
Shin-Osaka : Track 15 or 16 [Tokaido Line (JR Kobe Line), within 5 min.]
Osaka : Track 1 [Train NOT destined to Sakurajima, about 15 min.]
Shin-Imamiya : West Gate :-
Shin-Imamiya of Nankai : Track 3 [Local train, about 30 min.] Takaishi.
Here required time does not include waiting time.
210 yen: Fare for JR-West from Shin-Osaka to Shin-Imamiya.
370 yen: Fare for Nankai from Shin-Imamiya to Takaishi.