With an AVI type 2 capture you can capture the whole tape length in one go if you use NTFS disks. Even a 184 minute DVCAM tape can be captured in one go. There is no file limitation for capturing clips of this length. Personally I prefer to use scene detection to capture shorter clips, but that depends on your work flow and editing style.
Putting two clips from whatever length but to but in a time line is easy. They do not require rendering, unless effects were added, like colour correction. If you need an AVI from that, you need to export, but if your need is to export to DVD, forego the AVI creation and just export to MPEG2-DVD format.
Harm Millaard