request clarification of decoder parameters and simulation results

[qodesign]

Some basic questions (if these are documented somewhere please let me know) :

(Q1)in BpDecoder : dec = BpDecoder(H, error_rate=error_rate, max_iter=0, bp_method="minimum_sum")
what does max_iter=0 mean? I understand nonzero values.

(Q2)Are the BP and OSD decoders "independent"? I know BP can be done without OSD but OSD can also be done
without BP (I used OSD decoders (without BP) for BCH codes in the past). Is this the setup here?

(Q3)In OSD, how is the number of candidates determined? It seems to depend on "osd_method" and "osd_order".
So for "osd_method: "osd_cs" and "osd_oder : 42", what would the number of candidates be?
The c++ versions also has these other methods; I assume there's a different equation for each :
osdD->osd_method = ldpc::osd::OSD_0;
osdD->osd_method = ldpc::osd::EXHAUSTIVE;
osdD->osd_method = ldpc::osd::COMBINATION_SWEEP;

(Q4)For classical codes, what does "logical_error_rate" mean? is it word error rate or nonzero syndrome rate...