Joint Movie?

Hi,Guys…pls help i got a few question to ask.
i recently download a movie and it comes with 2 part (Dvdrip)

Q1:Can convertxtodvd joint the movie automatically or i have to joint the movie first before i try to convert it?
Q2:If the software can joint it,can we notice the joint sceen when it’s comes or it won’t be a diffrent (We won’t be seeing any diffrent)

Q3:The download also comes with 2 subtitle file,1 is in idx format another is sub.there are total of 4 file (2 idx,2 sub >>>because the movie comes with 2 part as i say on Q1&2)
How i going to add the subtitle in this kind of condition ?
Q4:i did try to convert a movie which comes with 2 subtitle file also(1idx,1sub),the information says it contain a few language after i convert the movie it just got english sub to display,am i missing some step st the setting ?
Anyone …? pls help

1: No - it is not joined technically, movie will be on disk as 2 tracks.
2: Changing from first track to second causes small pause; on most players this is barely noticeable.
3: Just add those movie parts, if those subs are in same directory with same name they will be picked automatically.
4: Changing subtitle language requires user to change them with DVD remote.