FLR further leave to remain - an extension of time on your visa. you shouldn't have to worry about this at all
If the financial standing of you is marginal, and if the applicant has plans to work in the UK, a job offer letter can be included to bolster the application's strength; and failing all other evidence, the applicant may attach a CV (or academic credentials) which demonstrate favorable prospects. Note however, that this is generally the weakest form of evidence.
well yes a letter offering a job would be very handy, as she will be allowed to work straight away on a spouse visa. the embassy could check with her employer thou. so i would probably mention your brother is her employer, that shouldn't be a problem, as i've seen that a few times..
their more concerned with you thou, you have a job, somewhere for her to live and hopefully some savings..
