Does Bloqs support ExpressionEngine's conditional fields?

No it does not, and probably never will. You can already create multiple bloqs with different atom/field variations, so adding conditionals fields into a bloq further complicates things (UI and code wise) for little gain. If ExpressionEngine does gain the ability to use conditional fields in complex custom field types we'll reevaluate the possibility.

Does Bloqs work with ExpressionEngine's database Find and Replace feature?

No it does not, but you can use the following queries as a guide to perform a find and replace on any Bloqs data.
# Replace content across all Bloqs content
UPDATE exp_blocks_atom SET `data`=(replace(`data`, 'old_value','new_value'));
# Replace content in a specific Atom
UPDATE exp_blocks_atom SET `data`=(replace (`data`, 'old_value','new_value')) where atomdefinition_id = "##";