Another Nice Sunset

.........not as spectacular as the one I missed last night due to procrastination but still acceptable.

My mum has asked me to help her with a written quiz that she is doing just for fun as part of one of the groups she belongs to but I'm struggling with a few clues.....so I'm asking you lovely people to exercise your brain cells and point me in the right direction, if you can :-)

Q1 - Subject heading is ' Book Titles'.....clue is...3.14159265359 and a tiger

Q2 - Subject heading is ' Book Titles'.......clue is...And so to bed and bring out your dead

Q3 - Subject heading is 'Countries'.........clue is...Archery and Mountains

Q4 -Subject heading is 'Garden'.........clue is...Pretty Polly Bulb

Q5 -  Subject heading is 'Nature'.........clue is...Vegetarian Martial Artist

Q6 - Subject heading is 'Nature'.......clue is ...Birds in evening dress

Thank you  :-)