(a) To find the number of ways to select the committee with exactly one of Mr Lan or Mrs Lan, we consider two cases:

1. Mr Lan is on the committee, but Mrs Lan is not. We choose 4 more members from the remaining 12 people (6 men and 6 women): \\(\binom{12}{4} = 495 \\\)
2. Mrs Lan is on the committee, but Mr Lan is not. We choose 4 more members from the remaining 12 people (6 men and 6 women): \\(\binom{12}{4} = 495 \\\)

Thus, the total number of ways is \\(495 + 495 = 990 \\\).

(b) If Mrs Lan must be on the committee and there must be more women than men, we consider the following scenarios:

1. 2 women and 2 men in addition to Mrs Lan: \\(\binom{7}{2} \times \binom{6}{2} = 315 \\\)
2. 3 women and 1 man in addition to Mrs Lan: \\(\binom{7}{3} \times \binom{6}{1} = 210 \\\)
3. 4 women in addition to Mrs Lan: \\(\binom{7}{4} = 35 \\\)

Adding these gives the total number of ways: \\(315 + 210 + 35 = 560 \\\).