Travellers cheques and cash (preferably US dollars) are the way to go in Indonesia. Credit cards are accepted by expensive hotels, restaurants and shops, but not for day-to-day expenses. In major centres, you can always find a bank that will advance cash on Visa or MasterCard. Credit card advances through ATMs are possible, but limited.
Tipping is not a normal practice in Indonesia but is often expected for special service. Someone who carries your bag or guides you around a tourist attraction will expect a tip. Jakarta taxi drivers expect you to round the fare up to the next 500 rp. Hotel porters expect a few hundred rupiah per bag.
Many everyday purchases normally require bargaining but in the current economic turmoil you'd do well to look to your conscience before applying this too stringently. Tourism has taken a severe downturn in most parts of the archipelago and, despite price hikes, hotel rooms are liable to be discounted.