1) and 2) should be the same, or you can also call it bit interval, which means the time of one bit
a symbol may include several bits, e.g. for binary signal, one symbol contains one bit, for M-ary signal, one symbol has log2(M) bits. so a symbol duration = bit duration * number of bits.
sample period should be the period between two samples, its inverse should be the sampling rate (or sampling frequency).
I will also like to know where 'chips,' which is the unit of 'spreading codes' in CDMA, fit in here 'physically' with respect to bit and symbol, bit rate and symbol rate?!