Ok here is my go at answering my own question: (see comments above & below for links)
Depending on what you want to do, GPL can be a bit complicated, with multiple versions, version numbers, and added exceptions over the years. it can be a headache. However, for this purposes of app development incorporating GPL/LGPL libraries, it is fairly straightforward. Keep in mind to check version numbers on all relevant documents, although they are most likely v3.0. As far as I know linking to a GPL library binds you to also releasing your code under GPL. So that is a no-go for closed source, but that brings me to my 1st question.
is it legal for me to remain closed source while incorporating
external libs that are both BSD and LGPL?
and I think the answer to that is yes provided that I dynamically link to said component (.so .dll .dylib .framework). Permission of this is granted under section 4d of LGPL v3.0.
d) Do one of the following:
0) Convey the Minimal Corresponding Source under the terms of this
License, and the Corresponding Application Code in a form
suitable for, and under terms that permit, the user to
recombine or relink the Application with a modified version of
the Linked Version to produce a modified Combined Work, in the
manner specified by section 6 of the GNU GPL for conveying
1) Use a suitable shared library mechanism for linking with the
Library. A suitable mechanism is one that (a) uses at run time
a copy of the Library already present on the user's computer
system, and (b) will operate properly with a modified version
of the Library that is interface-compatible with the Linked
My 2nd question
Would it change the ability for me to stay closed source if i were to use an altered version of one of these libraries?
It is my interpretation that in this case the only source you would need to provide is that of the modified library, and that the application itself can remain closed source. I'm basing this on grounds that nothing has changed from the situation for my 1st question other than the fact that the modified component library is now a derivative work under standard GPL v3.0.
finally my 3rd question
what is the legal effect on static vs dynamic linking?
This seams to be a bit iffy. Again see section 4d of the LGPL v3.0. By this wording dynamic linking is much preferable, and there are basically no requirements. If you choose to link statically though(in other words as part of the project build) things get complicated. To fully understand see LGPL definition of "Corresponding Application Code", and then see sections 4 5 and 6 of the GPL document. Full source is not required, but as far as i can tell you are required to provide all necessary materials for someone to build the project from scratch, so they can use a different version of the library if they so choose. This, in my opinion, would not be closed source.
I hope that is clear enough? I did quite a bit of looking around the internet in coming up with this answer, and in the end even some reading of the license, though I'm not sure I've actually read them through in there entirety. Keep in mind that there are multiple version of each license, and you should check version numbers for each LGPL library you use. There is a lot of good information on on opensource.stackexchange, although much more than one can process in a single sitting, and with occasional disagreement on finer points.
Below are some related links.