Here is a link to the models available from LaCie (I have a previous version):
http://www.lacie.com/us/products/range.htm?id=10014
At this time, there is no Blu-Ray listed.
I've checked your link and can't find any mention of Mac compatibility on the model BE08; however, I did find another model that specifically mentions Mac:
http://www.lge.com/products/model/detail/ge20.jhtml
I have no experience with LGE or blu-ray drives.
As for replacing the internal - if you are under warranty, you'll need to have it done at an authorized service provider (I have no idea as to the cost, but I'd guess $$$); if you purchase an external, you can use it with other computers and it should outlast your current Mac (mine has served me well with 3 iMacs, a Mini, and currently the iMac and MBP).